Difference between revisions of "IMO Problems and Solutions"
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| − | This page lists the authors of the problems of the [[International Mathematical Olympiad|IMO]]. | + | This page lists the authors and the proposing countries of the problems of the [[International Mathematical Olympiad|IMO]]. |
== 1959 == | == 1959 == | ||
* [[1959 IMO]] (in Romania) | * [[1959 IMO]] (in Romania) | ||
| − | |||
* [[1959 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | * [[1959 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | ||
* [[1959 IMO Problems/Problem 2 | Problem 2]] proposed by Constantin Ionescu-Tiu, Romania | * [[1959 IMO Problems/Problem 2 | Problem 2]] proposed by Constantin Ionescu-Tiu, Romania | ||
| Line 15: | Line 14: | ||
* [[1960 IMO]] (in Romania) | * [[1960 IMO]] (in Romania) | ||
| − | |||
* [[1960 IMO Problems/Problem 1 | Problem 1]] proposed by Bulgaria | * [[1960 IMO Problems/Problem 1 | Problem 1]] proposed by Bulgaria | ||
* [[1960 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | * [[1960 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | ||
| − | * [[1960 IMO Problems/Problem 3 | Problem 3]] proposed by | + | * [[1960 IMO Problems/Problem 3 | Problem 3]] proposed by Gheorghe D. Simionescu, Romania |
* [[1960 IMO Problems/Problem 4 | Problem 4]] proposed by Hungary | * [[1960 IMO Problems/Problem 4 | Problem 4]] proposed by Hungary | ||
* [[1960 IMO Problems/Problem 5 | Problem 5]] proposed by Czechoslovakia | * [[1960 IMO Problems/Problem 5 | Problem 5]] proposed by Czechoslovakia | ||
| Line 27: | Line 25: | ||
* [[1961 IMO]] (in Hungary) | * [[1961 IMO]] (in Hungary) | ||
| − | |||
* [[1961 IMO Problems/Problem 1 | Problem 1]] proposed by Hungary | * [[1961 IMO Problems/Problem 1 | Problem 1]] proposed by Hungary | ||
* [[1961 IMO Problems/Problem 2 | Problem 2]] proposed by Poland | * [[1961 IMO Problems/Problem 2 | Problem 2]] proposed by Poland | ||
| Line 33: | Line 30: | ||
* [[1961 IMO Problems/Problem 4 | Problem 4]] proposed by East Germany | * [[1961 IMO Problems/Problem 4 | Problem 4]] proposed by East Germany | ||
* [[1961 IMO Problems/Problem 5 | Problem 5]] proposed by Czechoslovakia | * [[1961 IMO Problems/Problem 5 | Problem 5]] proposed by Czechoslovakia | ||
| − | * [[1961 IMO Problems/Problem 6 | Problem 6]] proposed by | + | * [[1961 IMO Problems/Problem 6 | Problem 6]] proposed by Gheorghe D. Simionescu, Romania |
== 1962 == | == 1962 == | ||
* [[1962 IMO]] (in Czechoslovakia) | * [[1962 IMO]] (in Czechoslovakia) | ||
| − | |||
* [[1962 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | * [[1962 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | ||
* [[1962 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | * [[1962 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | ||
| Line 50: | Line 46: | ||
* [[1963 IMO]] (in Poland) | * [[1963 IMO]] (in Poland) | ||
| − | |||
* [[1963 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | * [[1963 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | ||
* [[1963 IMO Problems/Problem 2 | Problem 2]] proposed by USSR | * [[1963 IMO Problems/Problem 2 | Problem 2]] proposed by USSR | ||
| Line 61: | Line 56: | ||
* [[1964 IMO]] (in USSR) | * [[1964 IMO]] (in USSR) | ||
| − | |||
* [[1964 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | * [[1964 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | ||
* [[1964 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | * [[1964 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | ||
* [[1964 IMO Problems/Problem 3 | Problem 3]] proposed by Yugoslavia | * [[1964 IMO Problems/Problem 3 | Problem 3]] proposed by Yugoslavia | ||
* [[1964 IMO Problems/Problem 4 | Problem 4]] proposed by Hungary | * [[1964 IMO Problems/Problem 4 | Problem 4]] proposed by Hungary | ||
| − | * [[1964 IMO Problems/Problem 5 | Problem 5]] proposed by | + | * [[1964 IMO Problems/Problem 5 | Problem 5]] proposed by Gheorghe D. Simionescu, Romania |
* [[1964 IMO Problems/Problem 6 | Problem 6]] proposed by Poland | * [[1964 IMO Problems/Problem 6 | Problem 6]] proposed by Poland | ||
| Line 72: | Line 66: | ||
* [[1965 IMO]] (in East Germany) | * [[1965 IMO]] (in East Germany) | ||
| − | |||
* [[1965 IMO Problems/Problem 1 | Problem 1]] proposed by Yugoslavia | * [[1965 IMO Problems/Problem 1 | Problem 1]] proposed by Yugoslavia | ||
* [[1965 IMO Problems/Problem 2 | Problem 2]] proposed by Poland | * [[1965 IMO Problems/Problem 2 | Problem 2]] proposed by Poland | ||
* [[1965 IMO Problems/Problem 3 | Problem 3]] proposed by Czechoslovakia | * [[1965 IMO Problems/Problem 3 | Problem 3]] proposed by Czechoslovakia | ||
* [[1965 IMO Problems/Problem 4 | Problem 4]] proposed by USSR | * [[1965 IMO Problems/Problem 4 | Problem 4]] proposed by USSR | ||
| − | * [[1965 IMO Problems/Problem 5 | Problem 5]] proposed by | + | * [[1965 IMO Problems/Problem 5 | Problem 5]] proposed by Gheorghe D. Simionescu, Romania |
* [[1965 IMO Problems/Problem 6 | Problem 6]] proposed by Poland | * [[1965 IMO Problems/Problem 6 | Problem 6]] proposed by Poland | ||
| Line 83: | Line 76: | ||
* [[1966 IMO]] (in Bulgaria) | * [[1966 IMO]] (in Bulgaria) | ||
| − | |||
* [[1966 IMO Problems/Problem 1 | Problem 1]] proposed by USSR | * [[1966 IMO Problems/Problem 1 | Problem 1]] proposed by USSR | ||
* [[1966 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | * [[1966 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | ||
| Line 94: | Line 86: | ||
* [[1967 IMO]] (in Yugoslavia) | * [[1967 IMO]] (in Yugoslavia) | ||
| − | |||
* [[1967 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | * [[1967 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | ||
* [[1967 IMO Problems/Problem 2 | Problem 2]] proposed by Czechoslovakia | * [[1967 IMO Problems/Problem 2 | Problem 2]] proposed by Czechoslovakia | ||
| Line 104: | Line 95: | ||
== 1968 == | == 1968 == | ||
| − | * [[1968 IMO]] (in | + | * [[1968 IMO]] (in Russia) |
| − | |||
* [[1968 IMO Problems/Problem 1 | Problem 1]] proposed by Unknown Author, Romania (taken from a Romanian problem book) | * [[1968 IMO Problems/Problem 1 | Problem 1]] proposed by Unknown Author, Romania (taken from a Romanian problem book) | ||
* [[1968 IMO Problems/Problem 2 | Problem 2]] proposed by Czechoslovakia | * [[1968 IMO Problems/Problem 2 | Problem 2]] proposed by Czechoslovakia | ||
| Line 111: | Line 101: | ||
* [[1968 IMO Problems/Problem 4 | Problem 4]] proposed by Poland | * [[1968 IMO Problems/Problem 4 | Problem 4]] proposed by Poland | ||
* [[1968 IMO Problems/Problem 5 | Problem 5]] proposed by East Germany | * [[1968 IMO Problems/Problem 5 | Problem 5]] proposed by East Germany | ||
| − | * [[1968 IMO Problems/Problem 6 | Problem 6]] proposed by United Kingdom | + | * [[1968 IMO Problems/Problem 6 | Problem 6]] proposed by David Monk, United Kingdom |
== 1969 == | == 1969 == | ||
* [[1969 IMO]] (in Romania) | * [[1969 IMO]] (in Romania) | ||
| − | |||
* [[1969 IMO Problems/Problem 1 | Problem 1]] proposed by Wolfgang Engel, East Germany | * [[1969 IMO Problems/Problem 1 | Problem 1]] proposed by Wolfgang Engel, East Germany | ||
* [[1969 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | * [[1969 IMO Problems/Problem 2 | Problem 2]] proposed by Hungary | ||
| Line 127: | Line 116: | ||
* [[1970 IMO]] (in Hungary) | * [[1970 IMO]] (in Hungary) | ||
| − | |||
* [[1970 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | * [[1970 IMO Problems/Problem 1 | Problem 1]] proposed by Poland | ||
* [[1970 IMO Problems/Problem 2 | Problem 2]] proposed by Dumitru Batinetzu, Romania | * [[1970 IMO Problems/Problem 2 | Problem 2]] proposed by Dumitru Batinetzu, Romania | ||
| Line 138: | Line 126: | ||
* [[1971 IMO]] (in Czechoslovakia) | * [[1971 IMO]] (in Czechoslovakia) | ||
| − | |||
* [[1971 IMO Problems/Problem 1 | Problem 1]] proposed by Hungary | * [[1971 IMO Problems/Problem 1 | Problem 1]] proposed by Hungary | ||
* [[1971 IMO Problems/Problem 2 | Problem 2]] proposed by USSR | * [[1971 IMO Problems/Problem 2 | Problem 2]] proposed by USSR | ||
| Line 149: | Line 136: | ||
* [[1972 IMO]] (in Poland) | * [[1972 IMO]] (in Poland) | ||
| − | |||
* [[1972 IMO Problems/Problem 1 | Problem 1]] proposed by USSR | * [[1972 IMO Problems/Problem 1 | Problem 1]] proposed by USSR | ||
* [[1972 IMO Problems/Problem 2 | Problem 2]] proposed by Netherlands | * [[1972 IMO Problems/Problem 2 | Problem 2]] proposed by Netherlands | ||
| Line 160: | Line 146: | ||
* [[1973 IMO]] (in USSR) | * [[1973 IMO]] (in USSR) | ||
| − | |||
* [[1973 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | * [[1973 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | ||
* [[1973 IMO Problems/Problem 2 | Problem 2]] proposed by Poland | * [[1973 IMO Problems/Problem 2 | Problem 2]] proposed by Poland | ||
* [[1973 IMO Problems/Problem 3 | Problem 3]] proposed by Åke Samuelsson, Sweden | * [[1973 IMO Problems/Problem 3 | Problem 3]] proposed by Åke Samuelsson, Sweden | ||
| − | * [[1973 IMO Problems/Problem 4 | Problem 4]] proposed by Yugoslavia | + | * [[1973 IMO Problems/Problem 4 | Problem 4]] proposed by Ðorde Dugošija, Yugoslavia |
* [[1973 IMO Problems/Problem 5 | Problem 5]] proposed by Poland | * [[1973 IMO Problems/Problem 5 | Problem 5]] proposed by Poland | ||
* [[1973 IMO Problems/Problem 6 | Problem 6]] proposed by Åke Samuelsson, Sweden | * [[1973 IMO Problems/Problem 6 | Problem 6]] proposed by Åke Samuelsson, Sweden | ||
| Line 171: | Line 156: | ||
* [[1974 IMO]] (in East Germany) | * [[1974 IMO]] (in East Germany) | ||
| − | |||
* [[1974 IMO Problems/Problem 1 | Problem 1]] proposed by Murray Klamkin, USA | * [[1974 IMO Problems/Problem 1 | Problem 1]] proposed by Murray Klamkin, USA | ||
* [[1974 IMO Problems/Problem 2 | Problem 2]] proposed by Matti Lehtinen, Finland | * [[1974 IMO Problems/Problem 2 | Problem 2]] proposed by Matti Lehtinen, Finland | ||
| Line 182: | Line 166: | ||
* [[1975 IMO]] (in Bulgaria) | * [[1975 IMO]] (in Bulgaria) | ||
| − | |||
* [[1975 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | * [[1975 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | ||
* [[1975 IMO Problems/Problem 2 | Problem 2]] proposed by United Kingdom | * [[1975 IMO Problems/Problem 2 | Problem 2]] proposed by United Kingdom | ||
| Line 188: | Line 171: | ||
* [[1975 IMO Problems/Problem 4 | Problem 4]] proposed by USSR | * [[1975 IMO Problems/Problem 4 | Problem 4]] proposed by USSR | ||
* [[1975 IMO Problems/Problem 5 | Problem 5]] proposed by USSR | * [[1975 IMO Problems/Problem 5 | Problem 5]] proposed by USSR | ||
| − | * [[1975 IMO Problems/Problem 6 | Problem 6]] proposed by United Kingdom | + | * [[1975 IMO Problems/Problem 6 | Problem 6]] proposed by David Monk, United Kingdom |
== 1976 == | == 1976 == | ||
* [[1976 IMO]] (in Austria) | * [[1976 IMO]] (in Austria) | ||
| − | |||
* [[1976 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | * [[1976 IMO Problems/Problem 1 | Problem 1]] proposed by Czechoslovakia | ||
* [[1976 IMO Problems/Problem 2 | Problem 2]] proposed by Matti Lehtinen, Finland | * [[1976 IMO Problems/Problem 2 | Problem 2]] proposed by Matti Lehtinen, Finland | ||
| Line 199: | Line 181: | ||
* [[1976 IMO Problems/Problem 4 | Problem 4]] proposed by Murray Klamkin, USA | * [[1976 IMO Problems/Problem 4 | Problem 4]] proposed by Murray Klamkin, USA | ||
* [[1976 IMO Problems/Problem 5 | Problem 5]] proposed by Jan van de Craats, Netherlands | * [[1976 IMO Problems/Problem 5 | Problem 5]] proposed by Jan van de Craats, Netherlands | ||
| − | * [[1976 IMO Problems/Problem 6 | Problem 6]] proposed by United Kingdom | + | * [[1976 IMO Problems/Problem 6 | Problem 6]] proposed by Robert Lyness and David Monk, United Kingdom |
== 1977 == | == 1977 == | ||
* [[1977 IMO]] (in Yugoslavia) | * [[1977 IMO]] (in Yugoslavia) | ||
| − | |||
* [[1977 IMO Problems/Problem 1 | Problem 1]] proposed by Jan van de Craats, Netherlands | * [[1977 IMO Problems/Problem 1 | Problem 1]] proposed by Jan van de Craats, Netherlands | ||
* [[1977 IMO Problems/Problem 2 | Problem 2]] proposed by Phan Duc Chinh, Vietnam | * [[1977 IMO Problems/Problem 2 | Problem 2]] proposed by Phan Duc Chinh, Vietnam | ||
* [[1977 IMO Problems/Problem 3 | Problem 3]] proposed by Jan van de Craats, Netherlands | * [[1977 IMO Problems/Problem 3 | Problem 3]] proposed by Jan van de Craats, Netherlands | ||
| − | * [[1977 IMO Problems/Problem 4 | Problem 4]] proposed by United Kingdom | + | * [[1977 IMO Problems/Problem 4 | Problem 4]] proposed by David Monk, United Kingdom |
| − | * [[1977 IMO Problems/Problem 5 | Problem 5]] proposed by West Germany | + | * [[1977 IMO Problems/Problem 5 | Problem 5]] proposed by Hermann Frasch, West Germany |
* [[1977 IMO Problems/Problem 6 | Problem 6]] proposed by Ivan Prodanov, Bulgaria | * [[1977 IMO Problems/Problem 6 | Problem 6]] proposed by Ivan Prodanov, Bulgaria | ||
| Line 215: | Line 196: | ||
* [[1978 IMO]] (in Romania) | * [[1978 IMO]] (in Romania) | ||
| − | |||
* [[1978 IMO Problems/Problem 1 | Problem 1]] proposed by Cuba | * [[1978 IMO Problems/Problem 1 | Problem 1]] proposed by Cuba | ||
* [[1978 IMO Problems/Problem 2 | Problem 2]] proposed by Murray Klamkin, USA | * [[1978 IMO Problems/Problem 2 | Problem 2]] proposed by Murray Klamkin, USA | ||
| Line 225: | Line 205: | ||
== 1979 == | == 1979 == | ||
| − | * [[1979 IMO]] (in United Kingdom) | + | * [[1979 IMO]] (in the United Kingdom) |
| − | + | * [[1979 IMO Problems/Problem 1 | Problem 1]] proposed by Arthur Engel, West Germany | |
| − | * [[1979 IMO Problems/Problem 1 | Problem 1]] proposed by West Germany | ||
* [[1979 IMO Problems/Problem 2 | Problem 2]] proposed by Nickolay Khadzhiivanov and Nedjalko Nenov, Bulgaria | * [[1979 IMO Problems/Problem 2 | Problem 2]] proposed by Nickolay Khadzhiivanov and Nedjalko Nenov, Bulgaria | ||
| − | * [[1979 IMO Problems/Problem 3 | Problem 3]] proposed by USSR | + | * [[1979 IMO Problems/Problem 3 | Problem 3]] proposed by Nikolai Vasil'ev and Igor F. Sharygin, USSR |
* [[1979 IMO Problems/Problem 4 | Problem 4]] proposed by Murray Klamkin, USA | * [[1979 IMO Problems/Problem 4 | Problem 4]] proposed by Murray Klamkin, USA | ||
| − | * [[1979 IMO Problems/Problem 5 | Problem 5]] proposed by Israel | + | * [[1979 IMO Problems/Problem 5 | Problem 5]] proposed by Joe Gillis, Israel |
| − | * [[1979 IMO Problems/Problem 6 | Problem 6]] proposed by West Germany | + | * [[1979 IMO Problems/Problem 6 | Problem 6]] proposed by Arthur Engel, West Germany |
== 1980 == | == 1980 == | ||
| Line 241: | Line 220: | ||
* [[1981 IMO]] (in USA) | * [[1981 IMO]] (in USA) | ||
| − | + | * [[1981 IMO Problems/Problem 1 | Problem 1]] proposed by David Monk, United Kingdom | |
| − | * [[1981 IMO Problems/Problem 1 | Problem 1]] proposed by United Kingdom | + | * [[1981 IMO Problems/Problem 2 | Problem 2]] proposed by Arthur Engel, West Germany |
| − | * [[1981 IMO Problems/Problem 2 | Problem 2]] proposed by West Germany | ||
* [[1981 IMO Problems/Problem 3 | Problem 3]] proposed by Jan van de Craats, Netherlands | * [[1981 IMO Problems/Problem 3 | Problem 3]] proposed by Jan van de Craats, Netherlands | ||
* [[1981 IMO Problems/Problem 4 | Problem 4]] proposed by Belgium | * [[1981 IMO Problems/Problem 4 | Problem 4]] proposed by Belgium | ||
| Line 252: | Line 230: | ||
* [[1982 IMO]] (in Hungary) | * [[1982 IMO]] (in Hungary) | ||
| − | + | * [[1982 IMO Problems/Problem 1 | Problem 1]] proposed by David Monk, United Kingdom | |
| − | * [[1982 IMO Problems/Problem 1 | Problem 1]] proposed by United Kingdom | ||
* [[1982 IMO Problems/Problem 2 | Problem 2]] proposed by Jan van de Craats, Netherlands | * [[1982 IMO Problems/Problem 2 | Problem 2]] proposed by Jan van de Craats, Netherlands | ||
* [[1982 IMO Problems/Problem 3 | Problem 3]] proposed by Alexander N. Grishkov, USSR | * [[1982 IMO Problems/Problem 3 | Problem 3]] proposed by Alexander N. Grishkov, USSR | ||
| − | * [[1982 IMO Problems/Problem 4 | Problem 4]] proposed by United Kingdom | + | * [[1982 IMO Problems/Problem 4 | Problem 4]] proposed by David Monk, United Kingdom |
* [[1982 IMO Problems/Problem 5 | Problem 5]] proposed by Jan van de Craats, Netherlands | * [[1982 IMO Problems/Problem 5 | Problem 5]] proposed by Jan van de Craats, Netherlands | ||
* [[1982 IMO Problems/Problem 6 | Problem 6]] proposed by Van Nhu Cuong, Vietnam | * [[1982 IMO Problems/Problem 6 | Problem 6]] proposed by Van Nhu Cuong, Vietnam | ||
| Line 263: | Line 240: | ||
* [[1983 IMO]] (in France) | * [[1983 IMO]] (in France) | ||
| − | + | * [[1983 IMO Problems/Problem 1 | Problem 1]] proposed by David Monk, United Kingdom | |
| − | * [[1983 IMO Problems/Problem 1 | Problem 1]] proposed by United Kingdom | ||
* [[1983 IMO Problems/Problem 2 | Problem 2]] proposed by Igor F. Sharygin, USSR | * [[1983 IMO Problems/Problem 2 | Problem 2]] proposed by Igor F. Sharygin, USSR | ||
| − | * [[1983 IMO Problems/Problem 3 | Problem 3]] proposed by West Germany | + | * [[1983 IMO Problems/Problem 3 | Problem 3]] proposed by Arthur Engel, West Germany |
* [[1983 IMO Problems/Problem 4 | Problem 4]] proposed by Belgium | * [[1983 IMO Problems/Problem 4 | Problem 4]] proposed by Belgium | ||
* [[1983 IMO Problems/Problem 5 | Problem 5]] proposed by Marcin Kuczma, Poland | * [[1983 IMO Problems/Problem 5 | Problem 5]] proposed by Marcin Kuczma, Poland | ||
| Line 274: | Line 250: | ||
* [[1984 IMO]] (in Czechoslovakia) | * [[1984 IMO]] (in Czechoslovakia) | ||
| − | + | * [[1984 IMO Problems/Problem 1 | Problem 1]] proposed by Michael Stoll and Bruno Haible, West Germany | |
| − | * [[1984 IMO Problems/Problem 1 | Problem 1]] proposed by West Germany | ||
* [[1984 IMO Problems/Problem 2 | Problem 2]] proposed by Aiko Tiggelaar, Netherlands | * [[1984 IMO Problems/Problem 2 | Problem 2]] proposed by Aiko Tiggelaar, Netherlands | ||
* [[1984 IMO Problems/Problem 3 | Problem 3]] proposed by Ioan Tomescu, Romania | * [[1984 IMO Problems/Problem 3 | Problem 3]] proposed by Ioan Tomescu, Romania | ||
| Line 285: | Line 260: | ||
* [[1985 IMO]] (in Finland) | * [[1985 IMO]] (in Finland) | ||
| − | + | * [[1985 IMO Problems/Problem 1 | Problem 1]] proposed by Frank Budden, United Kingdom | |
| − | * [[1985 IMO Problems/Problem 1 | Problem 1]] proposed by United Kingdom | ||
* [[1985 IMO Problems/Problem 2 | Problem 2]] proposed by George Szekeres, Australia | * [[1985 IMO Problems/Problem 2 | Problem 2]] proposed by George Szekeres, Australia | ||
* [[1985 IMO Problems/Problem 3 | Problem 3]] proposed by Jan van de Craats, Netherlands | * [[1985 IMO Problems/Problem 3 | Problem 3]] proposed by Jan van de Craats, Netherlands | ||
* [[1985 IMO Problems/Problem 4 | Problem 4]] proposed by R. Gonchigdorj, Mongolia | * [[1985 IMO Problems/Problem 4 | Problem 4]] proposed by R. Gonchigdorj, Mongolia | ||
| − | * [[1985 IMO Problems/Problem 5 | Problem 5]] proposed by USSR | + | * [[1985 IMO Problems/Problem 5 | Problem 5]] proposed by Igor F. Sharygin, USSR |
* [[1985 IMO Problems/Problem 6 | Problem 6]] proposed by Åke Samuelsson, Sweden | * [[1985 IMO Problems/Problem 6 | Problem 6]] proposed by Åke Samuelsson, Sweden | ||
| Line 296: | Line 270: | ||
* [[1986 IMO]] (in Poland) | * [[1986 IMO]] (in Poland) | ||
| − | + | * [[1986 IMO Problems/Problem 1 | Problem 1]] proposed by Arthur Engel, West Germany | |
| − | * [[1986 IMO Problems/Problem 1 | Problem 1]] proposed by West Germany | ||
* [[1986 IMO Problems/Problem 2 | Problem 2]] proposed by Gengzhe Chang and Dongxu Qi, China | * [[1986 IMO Problems/Problem 2 | Problem 2]] proposed by Gengzhe Chang and Dongxu Qi, China | ||
* [[1986 IMO Problems/Problem 3 | Problem 3]] proposed by Elias Wegert, East Germany | * [[1986 IMO Problems/Problem 3 | Problem 3]] proposed by Elias Wegert, East Germany | ||
* [[1986 IMO Problems/Problem 4 | Problem 4]] proposed by Sven Sigurðsson, Iceland | * [[1986 IMO Problems/Problem 4 | Problem 4]] proposed by Sven Sigurðsson, Iceland | ||
| − | * [[1986 IMO Problems/Problem 5 | Problem 5]] proposed by United Kingdom | + | * [[1986 IMO Problems/Problem 5 | Problem 5]] proposed by David Monk, United Kingdom |
* [[1986 IMO Problems/Problem 6 | Problem 6]] proposed by Konrad Engel, East Germany | * [[1986 IMO Problems/Problem 6 | Problem 6]] proposed by Konrad Engel, East Germany | ||
| Line 307: | Line 280: | ||
* [[1987 IMO]] (in Cuba) | * [[1987 IMO]] (in Cuba) | ||
| − | |||
* [[1987 IMO Problems/Problem 1 | Problem 1]] proposed by Horst Sewerin, West Germany | * [[1987 IMO Problems/Problem 1 | Problem 1]] proposed by Horst Sewerin, West Germany | ||
* [[1987 IMO Problems/Problem 2 | Problem 2]] proposed by I.A. Kushnir, USSR | * [[1987 IMO Problems/Problem 2 | Problem 2]] proposed by I.A. Kushnir, USSR | ||
* [[1987 IMO Problems/Problem 3 | Problem 3]] proposed by Arthur Engel, West Germany | * [[1987 IMO Problems/Problem 3 | Problem 3]] proposed by Arthur Engel, West Germany | ||
* [[1987 IMO Problems/Problem 4 | Problem 4]] proposed by Nguyen Minh Duc, Vietnam | * [[1987 IMO Problems/Problem 4 | Problem 4]] proposed by Nguyen Minh Duc, Vietnam | ||
| − | * [[1987 IMO Problems/Problem 5 | Problem 5]] proposed by East Germany | + | * [[1987 IMO Problems/Problem 5 | Problem 5]] proposed by Hans-Dietrich Gronau, East Germany |
* [[1987 IMO Problems/Problem 6 | Problem 6]] proposed by Vsevolod F. Lev, USSR | * [[1987 IMO Problems/Problem 6 | Problem 6]] proposed by Vsevolod F. Lev, USSR | ||
| Line 318: | Line 290: | ||
* [[1988 IMO]] (in Australia) | * [[1988 IMO]] (in Australia) | ||
| − | |||
* [[1988 IMO Problems/Problem 1 | Problem 1]] proposed by Lucien Kieffer, Luxembourg | * [[1988 IMO Problems/Problem 1 | Problem 1]] proposed by Lucien Kieffer, Luxembourg | ||
* [[1988 IMO Problems/Problem 2 | Problem 2]] proposed by Czechoslovakia | * [[1988 IMO Problems/Problem 2 | Problem 2]] proposed by Czechoslovakia | ||
| − | * [[1988 IMO Problems/Problem 3 | Problem 3]] proposed by United Kingdom | + | * [[1988 IMO Problems/Problem 3 | Problem 3]] proposed by David Monk, United Kingdom |
* [[1988 IMO Problems/Problem 4 | Problem 4]] proposed by Finbarr Holland, Ireland | * [[1988 IMO Problems/Problem 4 | Problem 4]] proposed by Finbarr Holland, Ireland | ||
* [[1988 IMO Problems/Problem 5 | Problem 5]] proposed by Dimitris Kontogiannis, Greece | * [[1988 IMO Problems/Problem 5 | Problem 5]] proposed by Dimitris Kontogiannis, Greece | ||
| Line 329: | Line 300: | ||
* [[1989 IMO]] (in West Germany) | * [[1989 IMO]] (in West Germany) | ||
| − | + | * [[1989 IMO Problems/Problem 1 | Problem 1]] proposed by Severino Gervacio and Jose Marasigan, Philippines | |
| − | * [[1989 IMO Problems/Problem 1 | Problem 1]] proposed by Philippines | ||
* [[1989 IMO Problems/Problem 2 | Problem 2]] proposed by Esther Szekeres, Australia | * [[1989 IMO Problems/Problem 2 | Problem 2]] proposed by Esther Szekeres, Australia | ||
* [[1989 IMO Problems/Problem 3 | Problem 3]] proposed by Harm Derksen, Netherlands | * [[1989 IMO Problems/Problem 3 | Problem 3]] proposed by Harm Derksen, Netherlands | ||
| Line 340: | Line 310: | ||
* [[1990 IMO]] (in China) | * [[1990 IMO]] (in China) | ||
| − | |||
* [[1990 IMO Problems/Problem 1 | Problem 1]] proposed by C.R. Pranesachar, India | * [[1990 IMO Problems/Problem 1 | Problem 1]] proposed by C.R. Pranesachar, India | ||
* [[1990 IMO Problems/Problem 2 | Problem 2]] proposed by Pavol Černek, Czechoslovakia | * [[1990 IMO Problems/Problem 2 | Problem 2]] proposed by Pavol Černek, Czechoslovakia | ||
* [[1990 IMO Problems/Problem 3 | Problem 3]] proposed by Laurentiu Panaitopol, Romania | * [[1990 IMO Problems/Problem 3 | Problem 3]] proposed by Laurentiu Panaitopol, Romania | ||
* [[1990 IMO Problems/Problem 4 | Problem 4]] proposed by Albert Erkip, Turkey | * [[1990 IMO Problems/Problem 4 | Problem 4]] proposed by Albert Erkip, Turkey | ||
| − | * [[1990 IMO Problems/Problem 5 | Problem 5]] proposed by West Germany | + | * [[1990 IMO Problems/Problem 5 | Problem 5]] proposed by Hagen von Eitzen, West Germany |
* [[1990 IMO Problems/Problem 6 | Problem 6]] proposed by Harm Derksen, Netherlands | * [[1990 IMO Problems/Problem 6 | Problem 6]] proposed by Harm Derksen, Netherlands | ||
| Line 351: | Line 320: | ||
* [[1991 IMO]] (in Sweden) | * [[1991 IMO]] (in Sweden) | ||
| − | + | * [[1991 IMO Problems/Problem 1 | Problem 1]] proposed by Arkadii Skopenkov, USSR | |
| − | * [[1991 IMO Problems/Problem 1 | Problem 1]] proposed by USSR | ||
* [[1991 IMO Problems/Problem 2 | Problem 2]] proposed by Laurentiu Panaitopol, Romania | * [[1991 IMO Problems/Problem 2 | Problem 2]] proposed by Laurentiu Panaitopol, Romania | ||
* [[1991 IMO Problems/Problem 3 | Problem 3]] proposed by Chengzhang Li, China | * [[1991 IMO Problems/Problem 3 | Problem 3]] proposed by Chengzhang Li, China | ||
| Line 362: | Line 330: | ||
* [[1992 IMO]] (in Russia) | * [[1992 IMO]] (in Russia) | ||
| − | |||
* [[1992 IMO Problems/Problem 1 | Problem 1]] proposed by Achim Zulauf, New Zealand | * [[1992 IMO Problems/Problem 1 | Problem 1]] proposed by Achim Zulauf, New Zealand | ||
* [[1992 IMO Problems/Problem 2 | Problem 2]] proposed by Belur Jana Venkatachala, India | * [[1992 IMO Problems/Problem 2 | Problem 2]] proposed by Belur Jana Venkatachala, India | ||
| Line 373: | Line 340: | ||
* [[1993 IMO]] (in Turkey) | * [[1993 IMO]] (in Turkey) | ||
| − | |||
* [[1993 IMO Problems/Problem 1 | Problem 1]] proposed by Tom Laffey, Ireland | * [[1993 IMO Problems/Problem 1 | Problem 1]] proposed by Tom Laffey, Ireland | ||
* [[1993 IMO Problems/Problem 2 | Problem 2]] proposed by David Monk, United Kingdom | * [[1993 IMO Problems/Problem 2 | Problem 2]] proposed by David Monk, United Kingdom | ||
| Line 384: | Line 350: | ||
* [[1994 IMO]] (in Hong Kong) | * [[1994 IMO]] (in Hong Kong) | ||
| − | |||
* [[1994 IMO Problems/Problem 1 | Problem 1]] proposed by Vincent Lafforgue, France | * [[1994 IMO Problems/Problem 1 | Problem 1]] proposed by Vincent Lafforgue, France | ||
* [[1994 IMO Problems/Problem 2 | Problem 2]] proposed by Hans Lausch, Australia and Garnik Tonoyan, Armenia (independently) | * [[1994 IMO Problems/Problem 2 | Problem 2]] proposed by Hans Lausch, Australia and Garnik Tonoyan, Armenia (independently) | ||
* [[1994 IMO Problems/Problem 3 | Problem 3]] proposed by Gabriel Istrate, Romania | * [[1994 IMO Problems/Problem 3 | Problem 3]] proposed by Gabriel Istrate, Romania | ||
* [[1994 IMO Problems/Problem 4 | Problem 4]] proposed by Hans Lausch, Australia | * [[1994 IMO Problems/Problem 4 | Problem 4]] proposed by Hans Lausch, Australia | ||
| − | * [[1994 IMO Problems/Problem 5 | Problem 5]] proposed by United Kingdom | + | * [[1994 IMO Problems/Problem 5 | Problem 5]] proposed by David Monk, United Kingdom |
* [[1994 IMO Problems/Problem 6 | Problem 6]] proposed by Kerkko Luosto, Finland | * [[1994 IMO Problems/Problem 6 | Problem 6]] proposed by Kerkko Luosto, Finland | ||
| Line 395: | Line 360: | ||
* [[1995 IMO]] (in Canada) | * [[1995 IMO]] (in Canada) | ||
| − | |||
* [[1995 IMO Problems/Problem 1 | Problem 1]] proposed by Borislav Mihailov, Bulgaria | * [[1995 IMO Problems/Problem 1 | Problem 1]] proposed by Borislav Mihailov, Bulgaria | ||
* [[1995 IMO Problems/Problem 2 | Problem 2]] proposed by Nazar Agakhanov, Russia | * [[1995 IMO Problems/Problem 2 | Problem 2]] proposed by Nazar Agakhanov, Russia | ||
| Line 406: | Line 370: | ||
* [[1996 IMO]] (in India) | * [[1996 IMO]] (in India) | ||
| − | |||
* [[1996 IMO Problems/Problem 1 | Problem 1]] proposed by Kerkko Luosto, Finland | * [[1996 IMO Problems/Problem 1 | Problem 1]] proposed by Kerkko Luosto, Finland | ||
* [[1996 IMO Problems/Problem 2 | Problem 2]] proposed by Jeffrey Grossman, Canada | * [[1996 IMO Problems/Problem 2 | Problem 2]] proposed by Jeffrey Grossman, Canada | ||
| Line 417: | Line 380: | ||
* [[1997 IMO]] (in Argentina) | * [[1997 IMO]] (in Argentina) | ||
| − | + | * [[1997 IMO Problems/Problem 1 | Problem 1]] proposed by Igor Akylich and Igor Voronovich, Belarus | |
| − | * [[1997 IMO Problems/Problem 1 | Problem 1]] proposed by Igor Voronovich, Belarus | ||
* [[1997 IMO Problems/Problem 2 | Problem 2]] proposed by David Monk, United Kingdom | * [[1997 IMO Problems/Problem 2 | Problem 2]] proposed by David Monk, United Kingdom | ||
* [[1997 IMO Problems/Problem 3 | Problem 3]] proposed by Oleg Bogopolsky, Russia | * [[1997 IMO Problems/Problem 3 | Problem 3]] proposed by Oleg Bogopolsky, Russia | ||
| Line 428: | Line 390: | ||
* [[1998 IMO]] (in Taiwan) | * [[1998 IMO]] (in Taiwan) | ||
| − | + | * [[1998 IMO Problems/Problem 1 | Problem 1 (G1)]] proposed by Charles Leytem, Luxembourg | |
| − | * [[1998 IMO Problems/Problem 1 | Problem 1]] proposed by Charles Leytem, Luxembourg | + | * [[1998 IMO Problems/Problem 2 | Problem 2 (C5)]] proposed by Ravi B. Bapat, India |
| − | * [[1998 IMO Problems/Problem 2 | Problem 2]] proposed by | + | * [[1998 IMO Problems/Problem 3 | Problem 3 (N6)]] proposed by Igor Voronovich, Belarus |
| − | * [[1998 IMO Problems/Problem 3 | Problem 3]] proposed by Belarus | + | * [[1998 IMO Problems/Problem 4 | Problem 4 (N1)]] proposed by David Monk, United Kingdom |
| − | * [[1998 IMO Problems/Problem 4 | Problem 4]] proposed by David Monk, United Kingdom | + | * [[1998 IMO Problems/Problem 5 | Problem 5 (G3)]] proposed by Vyacheslav Yasinsky, Ukraine |
| − | * [[1998 IMO Problems/Problem 5 | Problem 5]] proposed by Ukraine | + | * [[1998 IMO Problems/Problem 6 | Problem 6 (A5)]] proposed by Oleg Mushkarov and Nikolai Nikolov, Bulgaria |
| − | * [[1998 IMO Problems/Problem 6 | Problem 6]] proposed by Oleg Mushkarov and Nikolai Nikolov, Bulgaria | ||
== 1999 == | == 1999 == | ||
* [[1999 IMO]] (in Romania) | * [[1999 IMO]] (in Romania) | ||
| − | + | * [[1999 IMO Problems/Problem 1 | Problem 1 (G3)]] proposed by Jan Willemson, Estonia | |
| − | * [[1999 IMO Problems/Problem 1 | Problem 1]] proposed by Jan Willemson, Estonia | + | * [[1999 IMO Problems/Problem 2 | Problem 2 (A1)]] proposed by Marcin Kuczma, Poland |
| − | * [[1999 IMO Problems/Problem 2 | Problem 2]] proposed by Marcin Kuczma, Poland | + | * [[1999 IMO Problems/Problem 3 | Problem 3 (C5)]] proposed by Eugenii Barabanov and Igor Voronovich, Belarus |
| − | * [[1999 IMO Problems/Problem 3 | Problem 3]] proposed by | + | * [[1999 IMO Problems/Problem 4 | Problem 4 (N1)]] proposed by Liang-Ju Chu, Taiwan |
| − | * [[1999 IMO Problems/Problem 4 | Problem 4]] proposed by Liang-Ju Chu, Taiwan | + | * [[1999 IMO Problems/Problem 5 | Problem 5 (G6)]] proposed by Pavel Kozhevnikov, Russia |
| − | * [[1999 IMO Problems/Problem 5 | Problem 5]] proposed by Pavel Kozhevnikov, Russia | + | * [[1999 IMO Problems/Problem 6 | Problem 6 (A5)]] proposed by Tetsuya Ando, Japan |
| − | * [[1999 IMO Problems/Problem 6 | Problem 6]] proposed by Tetsuya Ando, Japan | ||
== 2000 == | == 2000 == | ||
* [[2000 IMO]] (in South-Korea) | * [[2000 IMO]] (in South-Korea) | ||
| − | + | * [[2000 IMO Problems/Problem 1 | Problem 1 (G2)]] proposed by Sergei Berlov, Russia | |
| − | * [[2000 IMO Problems/Problem 1 | Problem 1]] proposed by Sergei Berlov, Russia | + | * [[2000 IMO Problems/Problem 2 | Problem 2 (A1)]] proposed by Titu Andreescu, USA |
| − | * [[2000 IMO Problems/Problem 2 | Problem 2]] proposed by Titu Andreescu, USA | + | * [[2000 IMO Problems/Problem 3 | Problem 3 (A5)]] proposed by Sergei Shikh and Igor Voronovich, Belarus |
| − | * [[2000 IMO Problems/Problem 3 | Problem 3]] proposed by Belarus | + | * [[2000 IMO Problems/Problem 4 | Problem 4 (C1)]] proposed by Sándor Dobos, Hungary |
| − | * [[2000 IMO Problems/Problem 4 | Problem 4]] proposed by Sándor Dobos, Hungary | + | * [[2000 IMO Problems/Problem 5 | Problem 5 (N3)]] proposed by Valerii Senderov, Russia |
| − | * [[2000 IMO Problems/Problem 5 | Problem 5]] proposed by Valerii Senderov, Russia | + | * [[2000 IMO Problems/Problem 6 | Problem 6 (G8)]] proposed by Lev and Tatiana Emelianovii, Russia |
| − | * [[2000 IMO Problems/Problem 6 | Problem 6]] proposed by Lev and Tatiana Emelianovii, Russia | ||
== 2001 == | == 2001 == | ||
* [[2001 IMO]] (in USA) | * [[2001 IMO]] (in USA) | ||
| − | + | * [[2001 IMO Problems/Problem 1 | Problem 1 (G2)]] proposed by Hojoo Lee, South Korea | |
| − | * [[2001 IMO Problems/Problem 1 | Problem 1]] proposed by Hojoo Lee, South Korea | + | * [[2001 IMO Problems/Problem 2 | Problem 2 (A6)]] proposed by Hojoo Lee, South Korea |
| − | * [[2001 IMO Problems/Problem 2 | Problem 2]] proposed by Hojoo Lee, South Korea | + | * [[2001 IMO Problems/Problem 3 | Problem 3 (C8)]] proposed by Christian Bey, Germany |
| − | * [[2001 IMO Problems/Problem 3 | Problem 3]] proposed by Christian Bey, Germany | + | * [[2001 IMO Problems/Problem 4 | Problem 4 (C2)]] proposed by Bill Sands, Canada |
| − | * [[2001 IMO Problems/Problem 4 | Problem 4]] proposed by Bill Sands, Canada | + | * [[2001 IMO Problems/Problem 5 | Problem 5 (G8)]] proposed by Shay Gueron, Israel. (Also: Problem 2501 in Crux Mathematicorum, February 2000) |
| − | * [[2001 IMO Problems/Problem 5 | Problem 5]] proposed by Israel | + | * [[2001 IMO Problems/Problem 6 | Problem 6 (N5)]] proposed by Aleksander Ivanov, Bulgaria |
| − | * [[2001 IMO Problems/Problem 6 | Problem 6]] proposed by Aleksander Ivanov, Bulgaria | ||
== 2002 == | == 2002 == | ||
| − | * [[2002 IMO]] (in United Kingdom) | + | * [[2002 IMO]] (in the United Kingdom) |
| − | + | * [[2002 IMO Problems/Problem 1 | Problem 1 (C1)]] proposed by Federico Ardila, Colombia | |
| − | * [[2002 IMO Problems/Problem 1 | Problem 1]] proposed by Federico Ardila, Colombia | + | * [[2002 IMO Problems/Problem 2 | Problem 2 (G3)]] proposed by Hojoo Lee, South Korea |
| − | * [[2002 IMO Problems/Problem 2 | Problem 2]] proposed by Hojoo Lee, South Korea | + | * [[2002 IMO Problems/Problem 3 | Problem 3 (N6)]] proposed by Laurentiu Panaitopol, Romania |
| − | * [[2002 IMO Problems/Problem 3 | Problem 3]] proposed by Laurentiu Panaitopol, Romania | + | * [[2002 IMO Problems/Problem 4 | Problem 4 (N2)]] proposed by Mihai Manea, Romania |
| − | * [[2002 IMO Problems/Problem 4 | Problem 4]] proposed by Mihai Manea, Romania | + | * [[2002 IMO Problems/Problem 5 | Problem 5 (A4)]] proposed by Belur Jana Venkatachala, India |
| − | * [[2002 IMO Problems/Problem 5 | Problem 5]] proposed by Belur Jana Venkatachala, India | + | * [[2002 IMO Problems/Problem 6 | Problem 6 (G6)]] proposed by Vyacheslav Yasinsky, Ukraine |
| − | * [[2002 IMO Problems/Problem 6 | Problem 6]] proposed by Vyacheslav Yasinsky, Ukraine | ||
== 2003 == | == 2003 == | ||
* [[2003 IMO]] (in Japan) | * [[2003 IMO]] (in Japan) | ||
| − | + | * [[2003 IMO Problems/Problem 1 | Problem 1 (C1)]] proposed by Carlos Gustavo Moreira, Brazil | |
| − | * [[2003 IMO Problems/Problem 1 | Problem 1]] proposed by Carlos Gustavo Moreira, Brazil | + | * [[2003 IMO Problems/Problem 2 | Problem 2 (N3)]] proposed by Aleksander Ivanov, Bulgaria |
| − | * [[2003 IMO Problems/Problem 2 | Problem 2]] proposed by Aleksander Ivanov, Bulgaria | + | * [[2003 IMO Problems/Problem 3 | Problem 3 (G6)]] proposed by Waldemar Pompe, Poland |
| − | * [[2003 IMO Problems/Problem 3 | Problem 3]] proposed by Waldemar Pompe, Poland | + | * [[2003 IMO Problems/Problem 4 | Problem 4 (G1)]] proposed by Matti Lehtinen, Finland |
| − | * [[2003 IMO Problems/Problem 4 | Problem 4]] proposed by Matti Lehtinen, Finland | + | * [[2003 IMO Problems/Problem 5 | Problem 5 (A4)]] proposed by Finbarr Holland, Ireland |
| − | * [[2003 IMO Problems/Problem 5 | Problem 5]] proposed by Finbarr Holland, Ireland | + | * [[2003 IMO Problems/Problem 6 | Problem 6 (N6)]] proposed by Johan Yebbou, France |
| − | * [[2003 IMO Problems/Problem 6 | Problem 6]] proposed by Johan Yebbou, France | ||
== 2004 == | == 2004 == | ||
* [[2004 IMO]] (in Greece) | * [[2004 IMO]] (in Greece) | ||
| − | + | * [[2004 IMO Problems/Problem 1 | Problem 1 (G1)]] proposed by Dinu Serbanescu and Valentin Vornicu, Romania | |
| − | * [[2004 IMO Problems/Problem 1 | Problem 1]] proposed by Valentin Vornicu | + | * [[2004 IMO Problems/Problem 2 | Problem 2 (A4)]] proposed by Hojoo Lee, South Korea |
| − | * [[2004 IMO Problems/Problem 2 | Problem 2]] proposed by Hojoo Lee, South Korea | + | * [[2004 IMO Problems/Problem 3 | Problem 3 (C7)]] proposed by Jan Willemson, Estonia |
| − | * [[2004 IMO Problems/Problem 3 | Problem 3]] proposed by Jan Willemson, Estonia | + | * [[2004 IMO Problems/Problem 4 | Problem 4 (A1)]] proposed by Hojoo Lee, South Korea |
| − | * [[2004 IMO Problems/Problem 4 | Problem 4]] proposed by Hojoo Lee, South Korea | + | * [[2004 IMO Problems/Problem 5 | Problem 5 (G4)]] proposed by Waldemar Pompe, Poland |
| − | * [[2004 IMO Problems/Problem 5 | Problem 5]] proposed by Waldemar Pompe, Poland | + | * [[2004 IMO Problems/Problem 6 | Problem 6 (N5)]] proposed by Mohsen Jamaali and Armin Morabbi, Iran |
| − | * [[2004 IMO Problems/Problem 6 | Problem 6]] proposed by Mohsen Jamaali and Armin Morabbi, Iran | ||
== 2005 == | == 2005 == | ||
* [[2005 IMO]] (in Mexico) | * [[2005 IMO]] (in Mexico) | ||
| − | + | * [[2005 IMO Problems/Problem 1 | Problem 1 (G2)]] proposed by Bogdan Enescu, Romania | |
| − | * [[2005 IMO Problems/Problem 1 | Problem 1]] proposed by Bogdan Enescu, Romania | + | * [[2005 IMO Problems/Problem 2 | Problem 2 (N2)]] proposed by Nicholas de Bruijn, Netherlands |
| − | * [[2005 IMO Problems/Problem 2 | Problem 2]] proposed by Nicholas de Bruijn, Netherlands | + | * [[2005 IMO Problems/Problem 3 | Problem 3 (A5)]] proposed by Hojoo Lee, South Korea |
| − | * [[2005 IMO Problems/Problem 3 | Problem 3]] proposed by Hojoo Lee, South Korea | + | * [[2005 IMO Problems/Problem 4 | Problem 4 (N1)]] proposed by Mariusz Skalba, Poland |
| − | * [[2005 IMO Problems/Problem 4 | Problem 4]] proposed by Mariusz Skalba, Poland | + | * [[2005 IMO Problems/Problem 5 | Problem 5 (G4)]] proposed by Waldemar Pompe, Poland |
| − | * [[2005 IMO Problems/Problem 5 | Problem 5]] proposed by Waldemar Pompe, Poland | + | * [[2005 IMO Problems/Problem 6 | Problem 6 (C6)]] proposed by Radu Gologan and Dan Schwarz, Romania |
| − | * [[2005 IMO Problems/Problem 6 | Problem 6]] proposed by Radu Gologan and Dan Schwarz, Romania | ||
== 2006 == | == 2006 == | ||
* [[2006 IMO]] (in Slovenia) | * [[2006 IMO]] (in Slovenia) | ||
| − | + | * [[2006 IMO Problems/Problem 1 | Problem 1 (G1)]] proposed by Hojoo Lee, South Korea | |
| − | * [[2006 IMO Problems/Problem 1 | Problem 1]] proposed by Hojoo Lee, South Korea | + | * [[2006 IMO Problems/Problem 2 | Problem 2 (C2)]] proposed by Dušan Djukić, Serbia |
| − | * [[2006 IMO Problems/Problem 2 | Problem 2]] proposed by Dušan Djukić, Serbia | + | * [[2006 IMO Problems/Problem 3 | Problem 3 (A6)]] proposed by Finbarr Holland, Ireland |
| − | * [[2006 IMO Problems/Problem 3 | Problem 3]] proposed by Finbarr Holland, Ireland | + | * [[2006 IMO Problems/Problem 4 | Problem 4 (N1)]] proposed by Zuming Feng, USA |
| − | * [[2006 IMO Problems/Problem 4 | Problem 4]] proposed by Zuming Feng, USA | + | * [[2006 IMO Problems/Problem 5 | Problem 5 (N4)]] proposed by Dan Schwarz, Romania |
| − | * [[2006 IMO Problems/Problem 5 | Problem 5]] proposed by Dan Schwarz, Romania | + | * [[2006 IMO Problems/Problem 6 | Problem 6 (G10)]] proposed by Dušan Djukić, Serbia |
| − | * [[2006 IMO Problems/Problem 6 | Problem 6]] proposed by Dušan Djukić, Serbia | ||
== 2007 == | == 2007 == | ||
* [[2007 IMO]] (in Vietnam) | * [[2007 IMO]] (in Vietnam) | ||
| − | + | * [[2007 IMO Problems/Problem 1 | Problem 1 (A1)]] proposed by Michael Albert, New Zealand | |
| − | * [[2007 IMO Problems/Problem 1 | Problem 1]] proposed by Michael Albert, New Zealand | + | * [[2007 IMO Problems/Problem 2 | Problem 2 (G4)]] proposed by Charles Leytem, Luxembourg |
| − | * [[2007 IMO Problems/Problem 2 | Problem 2]] proposed by Charles Leytem, Luxembourg | + | * [[2007 IMO Problems/Problem 3 | Problem 3 (C6)]] proposed by Vasily Astakhov, Russia |
| − | * [[2007 IMO Problems/Problem 3 | Problem 3]] proposed by Vasily Astakhov, Russia | + | * [[2007 IMO Problems/Problem 4 | Problem 4 (G1)]] proposed by Marek Pechal, Czech Republic |
| − | * [[2007 IMO Problems/Problem 4 | Problem 4]] proposed by Marek Pechal, Czech Republic | + | * [[2007 IMO Problems/Problem 5 | Problem 5 (N6)]] proposed by Kevin Buzzard and Edward Crane, United Kingdom |
| − | * [[2007 IMO Problems/Problem 5 | Problem 5]] proposed by Kevin Buzzard and Edward Crane, United Kingdom | + | * [[2007 IMO Problems/Problem 6 | Problem 6 (A7)]] proposed by Gerhard Woeginger, Netherlands |
| − | * [[2007 IMO Problems/Problem 6 | Problem 6]] proposed by Gerhard Woeginger, Netherlands | + | |
| + | == 2008 == | ||
| + | |||
| + | * [[2008 IMO]] (in Spain) | ||
| + | * [[2008 IMO Problems/Problem 1 | Problem 1 (G1)]] proposed by Andrey Gavrilyuk, Russia | ||
| + | * [[2008 IMO Problems/Problem 2 | Problem 2 (A2)]] proposed by Walther Janous, Austria | ||
| + | * [[2008 IMO Problems/Problem 3 | Problem 3 (N6)]] proposed by Kęstutis Česnavičius, Lithuania | ||
| + | * [[2008 IMO Problems/Problem 4 | Problem 4 (A1)]] proposed by Hojoo Lee, South Korea | ||
| + | * [[2008 IMO Problems/Problem 5 | Problem 5 (C4)]] proposed by Bruno Le Floch and Ilia Smilga, France | ||
| + | * [[2008 IMO Problems/Problem 6 | Problem 6 (G7)]] proposed by Vladimir Shmarov, Russia | ||
| + | |||
| + | == 2009 == | ||
| + | |||
| + | * [[2009 IMO]] (in Germany) | ||
| + | * [[2009 IMO Problems/Problem 1 | Problem 1 (N1)]] proposed by Ross Atkins, Australia | ||
| + | * [[2009 IMO Problems/Problem 2 | Problem 2 (G2)]] proposed by Sergei Berlov, Russia | ||
| + | * [[2009 IMO Problems/Problem 3 | Problem 3 (A6)]] proposed by Gabriel Carroll, USA | ||
| + | * [[2009 IMO Problems/Problem 4 | Problem 4 (G1)]] proposed by Hojoo Lee, Peter Vandendriessche and Jan Vonk, Belgium | ||
| + | * [[2009 IMO Problems/Problem 5 | Problem 5 (A3)]] proposed by Bruno Le Floch, France | ||
| + | * [[2009 IMO Problems/Problem 6 | Problem 6 (C7)]] proposed by Dmitry Khramtsov, Russia | ||
| + | |||
| + | == 2010 == | ||
| + | |||
| + | * [[2010 IMO]] (in Kazakhstan) | ||
| + | * [[2010 IMO Problems/Problem 1 | Problem 1 (A1)]] proposed by Pierre Bornsztein, France | ||
| + | * [[2010 IMO Problems/Problem 2 | Problem 2 (G4)]] proposed by Tai Wai Ming and Wang Chongli, Hong Kong | ||
| + | * [[2010 IMO Problems/Problem 3 | Problem 3 (N5)]] proposed by Gabriel Carroll, USA | ||
| + | * [[2010 IMO Problems/Problem 4 | Problem 4 (G2)]] proposed by Marcin Kuczma, Poland | ||
| + | * [[2010 IMO Problems/Problem 5 | Problem 5 (C4)]] proposed by Hans Zantema, Netherlands | ||
| + | * [[2010 IMO Problems/Problem 6 | Problem 6 (A7)]] proposed by Morteza Saghafiyan, Iran, Answer by Aadi | ||
| + | |||
| + | == 2011 == | ||
| + | |||
| + | * [[2011 IMO]] (in the Netherlands) | ||
| + | * [[2011 IMO Problems/Problem 1 | Problem 1 (A1)]] proposed by Fernando Campos, Mexico | ||
| + | * [[2011 IMO Problems/Problem 2 | Problem 2 (C3)]] proposed by Geoff Smith, United Kingdom | ||
| + | * [[2011 IMO Problems/Problem 3 | Problem 3 (A6)]] proposed by Igor Voronovich, Belarus | ||
| + | * [[2011 IMO Problems/Problem 4 | Problem 4 (C1)]] proposed by Morteza Saghafiyan, Iran | ||
| + | * [[2011 IMO Problems/Problem 5 | Problem 5 (N5)]] proposed by Seyedmahyar Sefidgaran, Iran | ||
| + | * [[2011 IMO Problems/Problem 6 | Problem 6 (G8)]] proposed by Japanese PSC, Japan | ||
| + | |||
| + | == 2012 == | ||
| + | |||
| + | * [[2012 IMO]] (in Argentina) | ||
| + | * [[2012 IMO Problems/Problem 1 | Problem 1 (G1)]] proposed by Evangelos Psychas, Greece | ||
| + | * [[2012 IMO Problems/Problem 2 | Problem 2 (A3)]] proposed by Angelo di Pasquale, Australia | ||
| + | * [[2012 IMO Problems/Problem 3 | Problem 3 (C6)]] proposed by David Arthur, Canada | ||
| + | * [[2012 IMO Problems/Problem 4 | Problem 4 (A1)]] proposed by Liam Baker, South Africa | ||
| + | * [[2012 IMO Problems/Problem 5 | Problem 5 (G5)]] proposed by Josef Tkadlec, Czech Republic | ||
| + | * [[2012 IMO Problems/Problem 6 | Problem 6 (N7)]] proposed by Dušan Djukić, Serbia | ||
| + | |||
| + | == 2013 == | ||
| + | |||
| + | * [[2013 IMO]] (in Colombia) | ||
| + | * [[2013 IMO Problems/Problem 1 | Problem 1 (N2)]] proposed by Japanese PSC, Japan | ||
| + | * [[2013 IMO Problems/Problem 2 | Problem 2 (C2)]] proposed by Ivan Guo, Australia | ||
| + | * [[2013 IMO Problems/Problem 3 | Problem 3 (G6)]] proposed by Alexander A. Polyansky, Russia | ||
| + | * [[2013 IMO Problems/Problem 4 | Problem 4 (G1)]] proposed by Warut Suksompong and Potcharapol Suteparuk, Thailand | ||
| + | * [[2013 IMO Problems/Problem 5 | Problem 5 (A3)]] proposed by Nikolai Nikolov, Bulgaria | ||
| + | * [[2013 IMO Problems/Problem 6 | Problem 6 (C7)]] proposed by Alexander S. Golovanov and Mikhail A. Ivanov, Russia | ||
| + | |||
| + | == 2014 == | ||
| + | |||
| + | * [[2014 IMO]] (in South Africa) | ||
| + | * [[2014 IMO Problems/Problem 1 | Problem 1 (A1)]] proposed by Gerhard Woeginger, Austria | ||
| + | * [[2014 IMO Problems/Problem 2 | Problem 2 (C3)]] proposed by Tonči Kokan, Croatia | ||
| + | * [[2014 IMO Problems/Problem 3 | Problem 3 (G5)]] proposed by Ali Zamani, Iran | ||
| + | * [[2014 IMO Problems/Problem 4 | Problem 4 (G1)]] proposed by Giorgi Arabidze, Georgia | ||
| + | * [[2014 IMO Problems/Problem 5 | Problem 5 (N3)]] proposed by Gerhard Woeginger, Luxembourg | ||
| + | * [[2014 IMO Problems/Problem 6 | Problem 6 (C5)]] proposed by Gerhard Woeginger, Austria | ||
| + | |||
| + | == 2015 == | ||
| + | |||
| + | * [[2015 IMO]] (in Thailand) | ||
| + | * [[2015 IMO Problems/Problem 1 | Problem 1 (C2)]] proposed by Merlijn Staps, Netherlands | ||
| + | * [[2015 IMO Problems/Problem 2 | Problem 2 (N5)]] proposed by Dušan Djukić, Serbia | ||
| + | * [[2015 IMO Problems/Problem 3 | Problem 3 (G6)]] proposed by Danylo Khilko and Mykhailo Plotnikov, Ukraine | ||
| + | * [[2015 IMO Problems/Problem 4 | Problem 4 (G2)]] proposed by Silouanos Brazitikos and Evangelos Psychas, Greece | ||
| + | * [[2015 IMO Problems/Problem 5 | Problem 5 (A4)]] proposed by Dorlir Ahmeti, Albania | ||
| + | * [[2015 IMO Problems/Problem 6 | Problem 6 (C5)]] proposed by Ross Atkins and Ivan Guo, Australia | ||
| + | |||
| + | == 2016 == | ||
| + | |||
| + | * [[2016 IMO]] (in Hong Kong) | ||
| + | * [[2016 IMO Problems/Problem 1 | Problem 1 (G1)]] proposed by Art Waeterschoot, Belgium | ||
| + | * [[2016 IMO Problems/Problem 2 | Problem 2 (C4)]] proposed by Trevor Tao, Australia | ||
| + | * [[2016 IMO Problems/Problem 3 | Problem 3 (N7)]] proposed by Aleksandr Gaifullin, Russia | ||
| + | * [[2016 IMO Problems/Problem 4 | Problem 4 (N3)]] proposed by Gerhard Woeginger, Luxembourg | ||
| + | * [[2016 IMO Problems/Problem 5 | Problem 5 (A6)]] proposed by Nazar Agakhanov and Ilya Bogdanov, Russia | ||
| + | * [[2016 IMO Problems/Problem 6 | Problem 6 (C7)]] proposed by Josef Tkadlec, Czech Republic | ||
| + | |||
| + | == 2017 == | ||
| + | |||
| + | * [[2017 IMO]] (in Brazil) | ||
| + | * [[2017 IMO Problems/Problem 1 | Problem 1 (N1)]] proposed by Stephan Wagner, South Africa | ||
| + | * [[2017 IMO Problems/Problem 2 | Problem 2 (A6)]] proposed by Dorlir Ahmeti, Albania | ||
| + | * [[2017 IMO Problems/Problem 3 | Problem 3 (C5)]] proposed by Gerhard Woeginger, Austria | ||
| + | * [[2017 IMO Problems/Problem 4 | Problem 4 (G2)]] proposed by Charles Leytem, Luxembourg | ||
| + | * [[2017 IMO Problems/Problem 5 | Problem 5 (C4)]] proposed by Grigory Chelnokov, Russia | ||
| + | * [[2017 IMO Problems/Problem 6 | Problem 6 (N7)]] proposed by John Berman, USA | ||
| + | |||
| + | == 2018 == | ||
| + | |||
| + | * [[2018 IMO]] (in Romania) | ||
| + | * [[2018 IMO Problems/Problem 1 | Problem 1 (G1)]] proposed by Silouanos Brazitikos, Evangelos Psychas and Michael Sarantis, Greece | ||
| + | * [[2018 IMO Problems/Problem 2 | Problem 2 (A2)]] proposed by Patrik Bak, Slovakia | ||
| + | * [[2018 IMO Problems/Problem 3 | Problem 3 (C4)]] proposed by Morteza Saghafian, Iran | ||
| + | * [[2018 IMO Problems/Problem 4 | Problem 4 (C2)]] proposed by Gurgen Asatryan, Armenia | ||
| + | * [[2018 IMO Problems/Problem 5 | Problem 5 (N4)]] proposed by Bayarmagnai Gombodorj, Mongolia | ||
| + | * [[2018 IMO Problems/Problem 6 | Problem 6 (G6)]] proposed by Tomasz Ciesla, Poland | ||
| + | |||
| + | == 2019 == | ||
| + | |||
| + | * [[2019 IMO]] (in the United Kingdom) | ||
| + | * [[2019 IMO Problems/Problem 1 | Problem 1 (A1)]] proposed by Liam Baker, South Africa | ||
| + | * [[2019 IMO Problems/Problem 2 | Problem 2 (G3)]] proposed by Anton Trygub, Ukraine | ||
| + | * [[2019 IMO Problems/Problem 3 | Problem 3 (C5)]] proposed by Adrian Beker, Croatia | ||
| + | * [[2019 IMO Problems/Problem 4 | Problem 4 (N1)]] proposed by Gabriel Chicas Reyes, El Salvador | ||
| + | * [[2019 IMO Problems/Problem 5 | Problem 5 (C3)]] proposed by David Altizio, USA | ||
| + | * [[2019 IMO Problems/Problem 6 | Problem 6 (G7)]] proposed by Anant Mudgal, India | ||
| + | |||
| + | == 2020 == | ||
| + | |||
| + | * [[2020 IMO]] (in Russia / virtual) | ||
| + | * [[2020 IMO Problems/Problem 1 | Problem 1 (G2)]] proposed by Dominik Burek, Poland | ||
| + | * [[2020 IMO Problems/Problem 2 | Problem 2 (A4)]] proposed by Stijn Cambie, Belgium | ||
| + | * [[2020 IMO Problems/Problem 3 | Problem 3 (C6)]] proposed by Milan Haiman and Carl Schildkraut, Hungary | ||
| + | * [[2020 IMO Problems/Problem 4 | Problem 4 (C3)]] proposed by Tejaswi Navrinarekallu, India | ||
| + | * [[2020 IMO Problems/Problem 5 | Problem 5 (N3)]] proposed by Oleg Košik, Estonia | ||
| + | * [[2020 IMO Problems/Problem 6 | Problem 6 (G9)]] proposed by Ting-Feng Lin and Hung-Hsun Hans Yu, Taiwan | ||
| + | |||
| + | == 2021 == | ||
| + | |||
| + | * [[2021 IMO]] (in Russia / virtual) | ||
| + | * [[2021 IMO Problems/Problem 1 | Problem 1 (N2)]] proposed by Australia | ||
| + | * [[2021 IMO Problems/Problem 2 | Problem 2 (A4)]] proposed by Calvin Deng, Canada | ||
| + | * [[2021 IMO Problems/Problem 3 | Problem 3 (G7)]] proposed by Mykhailo Shtandenko, Ukraine | ||
| + | * [[2021 IMO Problems/Problem 4 | Problem 4 (G2)]] proposed by Dominik Burek and Tomasz Ciesla, Poland | ||
| + | * [[2021 IMO Problems/Problem 5 | Problem 5 (C3)]] proposed by Spain | ||
| + | * [[2021 IMO Problems/Problem 6 | Problem 6 (A6)]] proposed by Austria | ||
| + | |||
| + | == 2022 == | ||
| + | |||
| + | * [[2022 IMO]] (in Norway) | ||
| + | * [[2022 IMO Problems/Problem 1 | Problem 1 (C2)]] proposed by France | ||
| + | * [[2022 IMO Problems/Problem 2 | Problem 2 (A3)]] proposed by Netherlands | ||
| + | * [[2022 IMO Problems/Problem 3 | Problem 3 (N7)]] proposed by USA | ||
| + | * [[2022 IMO Problems/Problem 4 | Problem 4 (G1)]] proposed by Slovakia | ||
| + | * [[2022 IMO Problems/Problem 5 | Problem 5 (N4)]] proposed by Belgium | ||
| + | * [[2022 IMO Problems/Problem 6 | Problem 6 (C8)]] proposed by Serbia | ||
| + | |||
| + | == 2023 == | ||
| + | |||
| + | * [[2023 IMO]] (in Japan) | ||
| + | * [[2023 IMO Problems/Problem 1 | Problem 1]] | ||
| + | * [[2023 IMO Problems/Problem 2 | Problem 2]] | ||
| + | * [[2023 IMO Problems/Problem 3 | Problem 3]] | ||
| + | * [[2023 IMO Problems/Problem 4 | Problem 4]] | ||
| + | * [[2023 IMO Problems/Problem 5 | Problem 5]] | ||
| + | * [[2023 IMO Problems/Problem 6 | Problem 6]] | ||
| + | |||
| + | == 2024 == | ||
| + | |||
| + | * [[2024 IMO]] (in UK) | ||
| + | * [[2024 IMO Problems/Problem 1 | Problem 1]] | ||
| + | * [[2024 IMO Problems/Problem 2 | Problem 2]] | ||
| + | * [[2024 IMO Problems/Problem 3 | Problem 3]] | ||
| + | * [[2024 IMO Problems/Problem 4 | Problem 4]] | ||
| + | * [[2024 IMO Problems/Problem 5 | Problem 5]] | ||
| + | * [[2024 IMO Problems/Problem 6 | Problem 6]] | ||
| + | |||
| + | == Comment == | ||
| + | |||
| + | This page lists the authors and the proposing countries of the problems of the [[International Mathematical Olympiad|IMO]]. | ||
| + | |||
| + | For many problems, the composers do not have the nationality of the proposing country. | ||
| + | For instance, problem 2009/4 was proposed by Belgium, but only two of the three problem authors were Belgian, whereas the third is from South-Korea. Similarly, problem 2020/3 was proposed by Hungary with one Hungarian and one non-Hungarian problem author. | ||
| + | |||
| + | To the current moment, there is only a single IMO problem that has two distinct proposing countries: The if-part of problem 1994/2 was proposed by Australia and its only-if part by Armenia. | ||
== See also == | == See also == | ||
| − | * [[IMO problems statistics]] | + | * [[IMO problems statistics]] (eternal) |
| − | * [ | + | * [[IMO problems statistics since 2000]] (modern history) |
| + | * [https://artofproblemsolving.com/community/c14_international_contests IMO problems on the Resources page] | ||
* [[IMO Shortlist Problems]] | * [[IMO Shortlist Problems]] | ||
* [[Academic Olympiads]] | * [[Academic Olympiads]] | ||
Latest revision as of 07:06, 4 August 2024
This page lists the authors and the proposing countries of the problems of the IMO.
Contents
- 1 1959
- 2 1960
- 3 1961
- 4 1962
- 5 1963
- 6 1964
- 7 1965
- 8 1966
- 9 1967
- 10 1968
- 11 1969
- 12 1970
- 13 1971
- 14 1972
- 15 1973
- 16 1974
- 17 1975
- 18 1976
- 19 1977
- 20 1978
- 21 1979
- 22 1980
- 23 1981
- 24 1982
- 25 1983
- 26 1984
- 27 1985
- 28 1986
- 29 1987
- 30 1988
- 31 1989
- 32 1990
- 33 1991
- 34 1992
- 35 1993
- 36 1994
- 37 1995
- 38 1996
- 39 1997
- 40 1998
- 41 1999
- 42 2000
- 43 2001
- 44 2002
- 45 2003
- 46 2004
- 47 2005
- 48 2006
- 49 2007
- 50 2008
- 51 2009
- 52 2010
- 53 2011
- 54 2012
- 55 2013
- 56 2014
- 57 2015
- 58 2016
- 59 2017
- 60 2018
- 61 2019
- 62 2020
- 63 2021
- 64 2022
- 65 2023
- 66 2024
- 67 Comment
- 68 See also
1959
- 1959 IMO (in Romania)
- Problem 1 proposed by Poland
- Problem 2 proposed by Constantin Ionescu-Tiu, Romania
- Problem 3 proposed by Hungary
- Problem 4 proposed by Hungary
- Problem 5 proposed by Cezar Cosnita, Romania
- Problem 6 proposed by Czechoslovakia
1960
- 1960 IMO (in Romania)
- Problem 1 proposed by Bulgaria
- Problem 2 proposed by Hungary
- Problem 3 proposed by Gheorghe D. Simionescu, Romania
- Problem 4 proposed by Hungary
- Problem 5 proposed by Czechoslovakia
- Problem 6 proposed by Bulgaria
- Problem 7 proposed by East Germany
1961
- 1961 IMO (in Hungary)
- Problem 1 proposed by Hungary
- Problem 2 proposed by Poland
- Problem 3 proposed by Bulgaria
- Problem 4 proposed by East Germany
- Problem 5 proposed by Czechoslovakia
- Problem 6 proposed by Gheorghe D. Simionescu, Romania
1962
- 1962 IMO (in Czechoslovakia)
- Problem 1 proposed by Poland
- Problem 2 proposed by Hungary
- Problem 3 proposed by Czechoslovakia
- Problem 4 proposed by Cezar Cosnita, Romania
- Problem 5 proposed by Bulgaria
- Problem 6 proposed by East Germany
- Problem 7 proposed by USSR
1963
- 1963 IMO (in Poland)
- Problem 1 proposed by Czechoslovakia
- Problem 2 proposed by USSR
- Problem 3 proposed by Hungary
- Problem 4 proposed by USSR
- Problem 5 proposed by Wolfgang Engel, East Germany
- Problem 6 proposed by Hungary
1964
- 1964 IMO (in USSR)
- Problem 1 proposed by Czechoslovakia
- Problem 2 proposed by Hungary
- Problem 3 proposed by Yugoslavia
- Problem 4 proposed by Hungary
- Problem 5 proposed by Gheorghe D. Simionescu, Romania
- Problem 6 proposed by Poland
1965
- 1965 IMO (in East Germany)
- Problem 1 proposed by Yugoslavia
- Problem 2 proposed by Poland
- Problem 3 proposed by Czechoslovakia
- Problem 4 proposed by USSR
- Problem 5 proposed by Gheorghe D. Simionescu, Romania
- Problem 6 proposed by Poland
1966
- 1966 IMO (in Bulgaria)
- Problem 1 proposed by USSR
- Problem 2 proposed by Hungary
- Problem 3 proposed by Bulgaria
- Problem 4 proposed by Yugoslavia
- Problem 5 proposed by Czechoslovakia
- Problem 6 proposed by Poland
1967
- 1967 IMO (in Yugoslavia)
- Problem 1 proposed by Poland
- Problem 2 proposed by Czechoslovakia
- Problem 3 proposed by United Kingdom
- Problem 4 proposed by Tullio Viola, Italy
- Problem 5 proposed by USSR
- Problem 6 proposed by Hungary
1968
- 1968 IMO (in Russia)
- Problem 1 proposed by Unknown Author, Romania (taken from a Romanian problem book)
- Problem 2 proposed by Czechoslovakia
- Problem 3 proposed by Bulgaria
- Problem 4 proposed by Poland
- Problem 5 proposed by East Germany
- Problem 6 proposed by David Monk, United Kingdom
1969
- 1969 IMO (in Romania)
- Problem 1 proposed by Wolfgang Engel, East Germany
- Problem 2 proposed by Hungary
- Problem 3 proposed by Poland
- Problem 4 proposed by Netherlands
- Problem 5 proposed by A. Mekei, Mongolia
- Problem 6 proposed by USSR
1970
- 1970 IMO (in Hungary)
- Problem 1 proposed by Poland
- Problem 2 proposed by Dumitru Batinetzu, Romania
- Problem 3 proposed by Åke Samuelsson, Sweden
- Problem 4 proposed by Czechoslovakia
- Problem 5 proposed by Bulgaria
- Problem 6 proposed by USSR
1971
- 1971 IMO (in Czechoslovakia)
- Problem 1 proposed by Hungary
- Problem 2 proposed by USSR
- Problem 3 proposed by Poland
- Problem 4 proposed by Netherlands
- Problem 5 proposed by Bulgaria
- Problem 6 proposed by Sweden
1972
- 1972 IMO (in Poland)
- Problem 1 proposed by USSR
- Problem 2 proposed by Netherlands
- Problem 3 proposed by United Kingdom
- Problem 4 proposed by Netherlands
- Problem 5 proposed by Bulgaria
- Problem 6 proposed by United Kingdom
1973
- 1973 IMO (in USSR)
- Problem 1 proposed by Czechoslovakia
- Problem 2 proposed by Poland
- Problem 3 proposed by Åke Samuelsson, Sweden
- Problem 4 proposed by Ðorde Dugošija, Yugoslavia
- Problem 5 proposed by Poland
- Problem 6 proposed by Åke Samuelsson, Sweden
1974
- 1974 IMO (in East Germany)
- Problem 1 proposed by Murray Klamkin, USA
- Problem 2 proposed by Matti Lehtinen, Finland
- Problem 3 proposed by Ciprian Borcea, Romania
- Problem 4 proposed by Bulgaria
- Problem 5 proposed by Jan van de Craats, Netherlands
- Problem 6 proposed by Sweden
1975
- 1975 IMO (in Bulgaria)
- Problem 1 proposed by Czechoslovakia
- Problem 2 proposed by United Kingdom
- Problem 3 proposed by Jan van de Craats, Netherlands
- Problem 4 proposed by USSR
- Problem 5 proposed by USSR
- Problem 6 proposed by David Monk, United Kingdom
1976
- 1976 IMO (in Austria)
- Problem 1 proposed by Czechoslovakia
- Problem 2 proposed by Matti Lehtinen, Finland
- Problem 3 proposed by Jan van de Craats, Netherlands
- Problem 4 proposed by Murray Klamkin, USA
- Problem 5 proposed by Jan van de Craats, Netherlands
- Problem 6 proposed by Robert Lyness and David Monk, United Kingdom
1977
- 1977 IMO (in Yugoslavia)
- Problem 1 proposed by Jan van de Craats, Netherlands
- Problem 2 proposed by Phan Duc Chinh, Vietnam
- Problem 3 proposed by Jan van de Craats, Netherlands
- Problem 4 proposed by David Monk, United Kingdom
- Problem 5 proposed by Hermann Frasch, West Germany
- Problem 6 proposed by Ivan Prodanov, Bulgaria
1978
- 1978 IMO (in Romania)
- Problem 1 proposed by Cuba
- Problem 2 proposed by Murray Klamkin, USA
- Problem 3 proposed by United Kingdom
- Problem 4 proposed by Murray Klamkin, USA
- Problem 5 proposed by France
- Problem 6 proposed by Jan van de Craats, Netherlands
1979
- 1979 IMO (in the United Kingdom)
- Problem 1 proposed by Arthur Engel, West Germany
- Problem 2 proposed by Nickolay Khadzhiivanov and Nedjalko Nenov, Bulgaria
- Problem 3 proposed by Nikolai Vasil'ev and Igor F. Sharygin, USSR
- Problem 4 proposed by Murray Klamkin, USA
- Problem 5 proposed by Joe Gillis, Israel
- Problem 6 proposed by Arthur Engel, West Germany
1980
1981
- 1981 IMO (in USA)
- Problem 1 proposed by David Monk, United Kingdom
- Problem 2 proposed by Arthur Engel, West Germany
- Problem 3 proposed by Jan van de Craats, Netherlands
- Problem 4 proposed by Belgium
- Problem 5 proposed by USSR
- Problem 6 proposed by Juha Oikkonen, Finland
1982
- 1982 IMO (in Hungary)
- Problem 1 proposed by David Monk, United Kingdom
- Problem 2 proposed by Jan van de Craats, Netherlands
- Problem 3 proposed by Alexander N. Grishkov, USSR
- Problem 4 proposed by David Monk, United Kingdom
- Problem 5 proposed by Jan van de Craats, Netherlands
- Problem 6 proposed by Van Nhu Cuong, Vietnam
1983
- 1983 IMO (in France)
- Problem 1 proposed by David Monk, United Kingdom
- Problem 2 proposed by Igor F. Sharygin, USSR
- Problem 3 proposed by Arthur Engel, West Germany
- Problem 4 proposed by Belgium
- Problem 5 proposed by Marcin Kuczma, Poland
- Problem 6 proposed by Murray Klamkin, USA
1984
- 1984 IMO (in Czechoslovakia)
- Problem 1 proposed by Michael Stoll and Bruno Haible, West Germany
- Problem 2 proposed by Aiko Tiggelaar, Netherlands
- Problem 3 proposed by Ioan Tomescu, Romania
- Problem 4 proposed by Laurentiu Panaitopol, Romania
- Problem 5 proposed by Tserendorj Dashdorj, Mongolia
- Problem 6 proposed by Poland
1985
- 1985 IMO (in Finland)
- Problem 1 proposed by Frank Budden, United Kingdom
- Problem 2 proposed by George Szekeres, Australia
- Problem 3 proposed by Jan van de Craats, Netherlands
- Problem 4 proposed by R. Gonchigdorj, Mongolia
- Problem 5 proposed by Igor F. Sharygin, USSR
- Problem 6 proposed by Åke Samuelsson, Sweden
1986
- 1986 IMO (in Poland)
- Problem 1 proposed by Arthur Engel, West Germany
- Problem 2 proposed by Gengzhe Chang and Dongxu Qi, China
- Problem 3 proposed by Elias Wegert, East Germany
- Problem 4 proposed by Sven Sigurðsson, Iceland
- Problem 5 proposed by David Monk, United Kingdom
- Problem 6 proposed by Konrad Engel, East Germany
1987
- 1987 IMO (in Cuba)
- Problem 1 proposed by Horst Sewerin, West Germany
- Problem 2 proposed by I.A. Kushnir, USSR
- Problem 3 proposed by Arthur Engel, West Germany
- Problem 4 proposed by Nguyen Minh Duc, Vietnam
- Problem 5 proposed by Hans-Dietrich Gronau, East Germany
- Problem 6 proposed by Vsevolod F. Lev, USSR
1988
- 1988 IMO (in Australia)
- Problem 1 proposed by Lucien Kieffer, Luxembourg
- Problem 2 proposed by Czechoslovakia
- Problem 3 proposed by David Monk, United Kingdom
- Problem 4 proposed by Finbarr Holland, Ireland
- Problem 5 proposed by Dimitris Kontogiannis, Greece
- Problem 6 proposed by Stephan Beck, West Germany
1989
- 1989 IMO (in West Germany)
- Problem 1 proposed by Severino Gervacio and Jose Marasigan, Philippines
- Problem 2 proposed by Esther Szekeres, Australia
- Problem 3 proposed by Harm Derksen, Netherlands
- Problem 4 proposed by Eggert Briem, Iceland
- Problem 5 proposed by Bernt Lindström, Sweden
- Problem 6 proposed by Marcin Kuczma, Poland
1990
- 1990 IMO (in China)
- Problem 1 proposed by C.R. Pranesachar, India
- Problem 2 proposed by Pavol Černek, Czechoslovakia
- Problem 3 proposed by Laurentiu Panaitopol, Romania
- Problem 4 proposed by Albert Erkip, Turkey
- Problem 5 proposed by Hagen von Eitzen, West Germany
- Problem 6 proposed by Harm Derksen, Netherlands
1991
- 1991 IMO (in Sweden)
- Problem 1 proposed by Arkadii Skopenkov, USSR
- Problem 2 proposed by Laurentiu Panaitopol, Romania
- Problem 3 proposed by Chengzhang Li, China
- Problem 4 proposed by Cecil Rousseau, USA
- Problem 5 proposed by Johan Yebbou, France
- Problem 6 proposed by Harm Derksen, Netherlands
1992
- 1992 IMO (in Russia)
- Problem 1 proposed by Achim Zulauf, New Zealand
- Problem 2 proposed by Belur Jana Venkatachala, India
- Problem 3 proposed by Chengzhang Li, China
- Problem 4 proposed by Johan Yebbou, France
- Problem 5 proposed by Stefano Mortola, Italy
- Problem 6 proposed by Tony Gardiner, United Kingdom
1993
- 1993 IMO (in Turkey)
- Problem 1 proposed by Tom Laffey, Ireland
- Problem 2 proposed by David Monk, United Kingdom
- Problem 3 proposed by Kerkko Luosto, Finland
- Problem 4 proposed by Donco Dimovski, Macedonia
- Problem 5 proposed by Elias Wegert, Germany
- Problem 6 proposed by Nicholas de Bruijn, Netherlands
1994
- 1994 IMO (in Hong Kong)
- Problem 1 proposed by Vincent Lafforgue, France
- Problem 2 proposed by Hans Lausch, Australia and Garnik Tonoyan, Armenia (independently)
- Problem 3 proposed by Gabriel Istrate, Romania
- Problem 4 proposed by Hans Lausch, Australia
- Problem 5 proposed by David Monk, United Kingdom
- Problem 6 proposed by Kerkko Luosto, Finland
1995
- 1995 IMO (in Canada)
- Problem 1 proposed by Borislav Mihailov, Bulgaria
- Problem 2 proposed by Nazar Agakhanov, Russia
- Problem 3 proposed by Jaromír Šimša, Czech Republic
- Problem 4 proposed by Marcin Kuczma, Poland
- Problem 5 proposed by Alastair McNaughton, New Zealand
- Problem 6 proposed by Marcin Kuczma, Poland
1996
- 1996 IMO (in India)
- Problem 1 proposed by Kerkko Luosto, Finland
- Problem 2 proposed by Jeffrey Grossman, Canada
- Problem 3 proposed by Mircea Becheanu, Romania
- Problem 4 proposed by Alexander S. Golovanov, Russia
- Problem 5 proposed by Nairi Sedrakyan, Armenia
- Problem 6 proposed by Laurent Rosaz, France
1997
- 1997 IMO (in Argentina)
- Problem 1 proposed by Igor Akylich and Igor Voronovich, Belarus
- Problem 2 proposed by David Monk, United Kingdom
- Problem 3 proposed by Oleg Bogopolsky, Russia
- Problem 4 proposed by Ebadollah S. Mahmoodian and Mohammad Mahdian, Iran
- Problem 5 proposed by Petr Kanovsky, Czech Republic
- Problem 6 proposed by Giedrius Alkauskas, Lithuania
1998
- 1998 IMO (in Taiwan)
- Problem 1 (G1) proposed by Charles Leytem, Luxembourg
- Problem 2 (C5) proposed by Ravi B. Bapat, India
- Problem 3 (N6) proposed by Igor Voronovich, Belarus
- Problem 4 (N1) proposed by David Monk, United Kingdom
- Problem 5 (G3) proposed by Vyacheslav Yasinsky, Ukraine
- Problem 6 (A5) proposed by Oleg Mushkarov and Nikolai Nikolov, Bulgaria
1999
- 1999 IMO (in Romania)
- Problem 1 (G3) proposed by Jan Willemson, Estonia
- Problem 2 (A1) proposed by Marcin Kuczma, Poland
- Problem 3 (C5) proposed by Eugenii Barabanov and Igor Voronovich, Belarus
- Problem 4 (N1) proposed by Liang-Ju Chu, Taiwan
- Problem 5 (G6) proposed by Pavel Kozhevnikov, Russia
- Problem 6 (A5) proposed by Tetsuya Ando, Japan
2000
- 2000 IMO (in South-Korea)
- Problem 1 (G2) proposed by Sergei Berlov, Russia
- Problem 2 (A1) proposed by Titu Andreescu, USA
- Problem 3 (A5) proposed by Sergei Shikh and Igor Voronovich, Belarus
- Problem 4 (C1) proposed by Sándor Dobos, Hungary
- Problem 5 (N3) proposed by Valerii Senderov, Russia
- Problem 6 (G8) proposed by Lev and Tatiana Emelianovii, Russia
2001
- 2001 IMO (in USA)
- Problem 1 (G2) proposed by Hojoo Lee, South Korea
- Problem 2 (A6) proposed by Hojoo Lee, South Korea
- Problem 3 (C8) proposed by Christian Bey, Germany
- Problem 4 (C2) proposed by Bill Sands, Canada
- Problem 5 (G8) proposed by Shay Gueron, Israel. (Also: Problem 2501 in Crux Mathematicorum, February 2000)
- Problem 6 (N5) proposed by Aleksander Ivanov, Bulgaria
2002
- 2002 IMO (in the United Kingdom)
- Problem 1 (C1) proposed by Federico Ardila, Colombia
- Problem 2 (G3) proposed by Hojoo Lee, South Korea
- Problem 3 (N6) proposed by Laurentiu Panaitopol, Romania
- Problem 4 (N2) proposed by Mihai Manea, Romania
- Problem 5 (A4) proposed by Belur Jana Venkatachala, India
- Problem 6 (G6) proposed by Vyacheslav Yasinsky, Ukraine
2003
- 2003 IMO (in Japan)
- Problem 1 (C1) proposed by Carlos Gustavo Moreira, Brazil
- Problem 2 (N3) proposed by Aleksander Ivanov, Bulgaria
- Problem 3 (G6) proposed by Waldemar Pompe, Poland
- Problem 4 (G1) proposed by Matti Lehtinen, Finland
- Problem 5 (A4) proposed by Finbarr Holland, Ireland
- Problem 6 (N6) proposed by Johan Yebbou, France
2004
- 2004 IMO (in Greece)
- Problem 1 (G1) proposed by Dinu Serbanescu and Valentin Vornicu, Romania
- Problem 2 (A4) proposed by Hojoo Lee, South Korea
- Problem 3 (C7) proposed by Jan Willemson, Estonia
- Problem 4 (A1) proposed by Hojoo Lee, South Korea
- Problem 5 (G4) proposed by Waldemar Pompe, Poland
- Problem 6 (N5) proposed by Mohsen Jamaali and Armin Morabbi, Iran
2005
- 2005 IMO (in Mexico)
- Problem 1 (G2) proposed by Bogdan Enescu, Romania
- Problem 2 (N2) proposed by Nicholas de Bruijn, Netherlands
- Problem 3 (A5) proposed by Hojoo Lee, South Korea
- Problem 4 (N1) proposed by Mariusz Skalba, Poland
- Problem 5 (G4) proposed by Waldemar Pompe, Poland
- Problem 6 (C6) proposed by Radu Gologan and Dan Schwarz, Romania
2006
- 2006 IMO (in Slovenia)
- Problem 1 (G1) proposed by Hojoo Lee, South Korea
- Problem 2 (C2) proposed by Dušan Djukić, Serbia
- Problem 3 (A6) proposed by Finbarr Holland, Ireland
- Problem 4 (N1) proposed by Zuming Feng, USA
- Problem 5 (N4) proposed by Dan Schwarz, Romania
- Problem 6 (G10) proposed by Dušan Djukić, Serbia
2007
- 2007 IMO (in Vietnam)
- Problem 1 (A1) proposed by Michael Albert, New Zealand
- Problem 2 (G4) proposed by Charles Leytem, Luxembourg
- Problem 3 (C6) proposed by Vasily Astakhov, Russia
- Problem 4 (G1) proposed by Marek Pechal, Czech Republic
- Problem 5 (N6) proposed by Kevin Buzzard and Edward Crane, United Kingdom
- Problem 6 (A7) proposed by Gerhard Woeginger, Netherlands
2008
- 2008 IMO (in Spain)
- Problem 1 (G1) proposed by Andrey Gavrilyuk, Russia
- Problem 2 (A2) proposed by Walther Janous, Austria
- Problem 3 (N6) proposed by Kęstutis Česnavičius, Lithuania
- Problem 4 (A1) proposed by Hojoo Lee, South Korea
- Problem 5 (C4) proposed by Bruno Le Floch and Ilia Smilga, France
- Problem 6 (G7) proposed by Vladimir Shmarov, Russia
2009
- 2009 IMO (in Germany)
- Problem 1 (N1) proposed by Ross Atkins, Australia
- Problem 2 (G2) proposed by Sergei Berlov, Russia
- Problem 3 (A6) proposed by Gabriel Carroll, USA
- Problem 4 (G1) proposed by Hojoo Lee, Peter Vandendriessche and Jan Vonk, Belgium
- Problem 5 (A3) proposed by Bruno Le Floch, France
- Problem 6 (C7) proposed by Dmitry Khramtsov, Russia
2010
- 2010 IMO (in Kazakhstan)
- Problem 1 (A1) proposed by Pierre Bornsztein, France
- Problem 2 (G4) proposed by Tai Wai Ming and Wang Chongli, Hong Kong
- Problem 3 (N5) proposed by Gabriel Carroll, USA
- Problem 4 (G2) proposed by Marcin Kuczma, Poland
- Problem 5 (C4) proposed by Hans Zantema, Netherlands
- Problem 6 (A7) proposed by Morteza Saghafiyan, Iran, Answer by Aadi
2011
- 2011 IMO (in the Netherlands)
- Problem 1 (A1) proposed by Fernando Campos, Mexico
- Problem 2 (C3) proposed by Geoff Smith, United Kingdom
- Problem 3 (A6) proposed by Igor Voronovich, Belarus
- Problem 4 (C1) proposed by Morteza Saghafiyan, Iran
- Problem 5 (N5) proposed by Seyedmahyar Sefidgaran, Iran
- Problem 6 (G8) proposed by Japanese PSC, Japan
2012
- 2012 IMO (in Argentina)
- Problem 1 (G1) proposed by Evangelos Psychas, Greece
- Problem 2 (A3) proposed by Angelo di Pasquale, Australia
- Problem 3 (C6) proposed by David Arthur, Canada
- Problem 4 (A1) proposed by Liam Baker, South Africa
- Problem 5 (G5) proposed by Josef Tkadlec, Czech Republic
- Problem 6 (N7) proposed by Dušan Djukić, Serbia
2013
- 2013 IMO (in Colombia)
- Problem 1 (N2) proposed by Japanese PSC, Japan
- Problem 2 (C2) proposed by Ivan Guo, Australia
- Problem 3 (G6) proposed by Alexander A. Polyansky, Russia
- Problem 4 (G1) proposed by Warut Suksompong and Potcharapol Suteparuk, Thailand
- Problem 5 (A3) proposed by Nikolai Nikolov, Bulgaria
- Problem 6 (C7) proposed by Alexander S. Golovanov and Mikhail A. Ivanov, Russia
2014
- 2014 IMO (in South Africa)
- Problem 1 (A1) proposed by Gerhard Woeginger, Austria
- Problem 2 (C3) proposed by Tonči Kokan, Croatia
- Problem 3 (G5) proposed by Ali Zamani, Iran
- Problem 4 (G1) proposed by Giorgi Arabidze, Georgia
- Problem 5 (N3) proposed by Gerhard Woeginger, Luxembourg
- Problem 6 (C5) proposed by Gerhard Woeginger, Austria
2015
- 2015 IMO (in Thailand)
- Problem 1 (C2) proposed by Merlijn Staps, Netherlands
- Problem 2 (N5) proposed by Dušan Djukić, Serbia
- Problem 3 (G6) proposed by Danylo Khilko and Mykhailo Plotnikov, Ukraine
- Problem 4 (G2) proposed by Silouanos Brazitikos and Evangelos Psychas, Greece
- Problem 5 (A4) proposed by Dorlir Ahmeti, Albania
- Problem 6 (C5) proposed by Ross Atkins and Ivan Guo, Australia
2016
- 2016 IMO (in Hong Kong)
- Problem 1 (G1) proposed by Art Waeterschoot, Belgium
- Problem 2 (C4) proposed by Trevor Tao, Australia
- Problem 3 (N7) proposed by Aleksandr Gaifullin, Russia
- Problem 4 (N3) proposed by Gerhard Woeginger, Luxembourg
- Problem 5 (A6) proposed by Nazar Agakhanov and Ilya Bogdanov, Russia
- Problem 6 (C7) proposed by Josef Tkadlec, Czech Republic
2017
- 2017 IMO (in Brazil)
- Problem 1 (N1) proposed by Stephan Wagner, South Africa
- Problem 2 (A6) proposed by Dorlir Ahmeti, Albania
- Problem 3 (C5) proposed by Gerhard Woeginger, Austria
- Problem 4 (G2) proposed by Charles Leytem, Luxembourg
- Problem 5 (C4) proposed by Grigory Chelnokov, Russia
- Problem 6 (N7) proposed by John Berman, USA
2018
- 2018 IMO (in Romania)
- Problem 1 (G1) proposed by Silouanos Brazitikos, Evangelos Psychas and Michael Sarantis, Greece
- Problem 2 (A2) proposed by Patrik Bak, Slovakia
- Problem 3 (C4) proposed by Morteza Saghafian, Iran
- Problem 4 (C2) proposed by Gurgen Asatryan, Armenia
- Problem 5 (N4) proposed by Bayarmagnai Gombodorj, Mongolia
- Problem 6 (G6) proposed by Tomasz Ciesla, Poland
2019
- 2019 IMO (in the United Kingdom)
- Problem 1 (A1) proposed by Liam Baker, South Africa
- Problem 2 (G3) proposed by Anton Trygub, Ukraine
- Problem 3 (C5) proposed by Adrian Beker, Croatia
- Problem 4 (N1) proposed by Gabriel Chicas Reyes, El Salvador
- Problem 5 (C3) proposed by David Altizio, USA
- Problem 6 (G7) proposed by Anant Mudgal, India
2020
- 2020 IMO (in Russia / virtual)
- Problem 1 (G2) proposed by Dominik Burek, Poland
- Problem 2 (A4) proposed by Stijn Cambie, Belgium
- Problem 3 (C6) proposed by Milan Haiman and Carl Schildkraut, Hungary
- Problem 4 (C3) proposed by Tejaswi Navrinarekallu, India
- Problem 5 (N3) proposed by Oleg Košik, Estonia
- Problem 6 (G9) proposed by Ting-Feng Lin and Hung-Hsun Hans Yu, Taiwan
2021
- 2021 IMO (in Russia / virtual)
- Problem 1 (N2) proposed by Australia
- Problem 2 (A4) proposed by Calvin Deng, Canada
- Problem 3 (G7) proposed by Mykhailo Shtandenko, Ukraine
- Problem 4 (G2) proposed by Dominik Burek and Tomasz Ciesla, Poland
- Problem 5 (C3) proposed by Spain
- Problem 6 (A6) proposed by Austria
2022
- 2022 IMO (in Norway)
- Problem 1 (C2) proposed by France
- Problem 2 (A3) proposed by Netherlands
- Problem 3 (N7) proposed by USA
- Problem 4 (G1) proposed by Slovakia
- Problem 5 (N4) proposed by Belgium
- Problem 6 (C8) proposed by Serbia
2023
2024
Comment
This page lists the authors and the proposing countries of the problems of the IMO.
For many problems, the composers do not have the nationality of the proposing country. For instance, problem 2009/4 was proposed by Belgium, but only two of the three problem authors were Belgian, whereas the third is from South-Korea. Similarly, problem 2020/3 was proposed by Hungary with one Hungarian and one non-Hungarian problem author.
To the current moment, there is only a single IMO problem that has two distinct proposing countries: The if-part of problem 1994/2 was proposed by Australia and its only-if part by Armenia.
