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− | ===[[ | + | ===[[Rearrangement Inequality]]=== |
− | ''' | + | The '''Rearrangement Inequality''' states that, if <math>A=\{a_1,a_2,\cdots,a_n\}</math> is a [[permutation]] of a [[finite]] [[set]] (in fact, [[multiset]]) of [[real number]]s and <math>B=\{b_1,b_2,\cdots,b_n\}</math> is a permutation of another finite set of real numbers, the quantity <math>a_1b_1+a_2b_2+\cdots+a_nb_n</math> is maximized when <math>{A}</math> and <math>{B} </math> are similarly sorted (that is, if <math>a_k</math> is greater than or equal to exactly <math>{i}</math> of the other members of <math>A</math>, then <math> {b_k} </math> is also greater than or equal to exactly <math>{i}</math> of the other members of <math>B</math>). Conversely, <math>a_1b_1+a_2b_2+\cdots+a_nb_n</math> is minimized when <math>A</math> and <math>B</math> are oppositely sorted (that is, if <math>a_k</math> is less than or equal |
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Revision as of 22:05, 13 December 2007
Rearrangement Inequality
The Rearrangement Inequality states that, if is a permutation of a finite set (in fact, multiset) of real numbers and is a permutation of another finite set of real numbers, the quantity is maximized when and are similarly sorted (that is, if is greater than or equal to exactly of the other members of , then is also greater than or equal to exactly of the other members of ). Conversely, is minimized when and are oppositely sorted (that is, if is less than or equal