Difference between revisions of "Least upper bound"
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− | Given a [[subset]] <math>S</math> in some larger [[ordered set]] <math>R</math>, a '''least upper bound''' or '''supremum''' for <math>S</math> is an [[element]] <math>M \in R</math> such that <math>s \leq M</math> for every <math>s \in S</math> and there is no <math>m < M</math> with this same property. | + | Given a [[subset]] <math>S</math> in some larger [[ordered set]] <math>R</math>, a '''least upper bound''' or '''supremum''' for <math>S</math> is an [[element]] <math>\displaystyle M \in R</math> such that <math>s \leq M</math> for every <math>s \in S</math> and there is no <math>m < M</math> with this same property. |
If the least upper bound <math>M</math> of <math>S</math> is an element of <math>S</math>, it is also the [[maximum]] of <math>S</math>. If <math>M \not\in S</math>, then <math>S</math> has no maximum. | If the least upper bound <math>M</math> of <math>S</math> is an element of <math>S</math>, it is also the [[maximum]] of <math>S</math>. If <math>M \not\in S</math>, then <math>S</math> has no maximum. |
Revision as of 19:19, 3 November 2006
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Given a subset in some larger ordered set
, a least upper bound or supremum for
is an element
such that
for every
and there is no
with this same property.
If the least upper bound of
is an element of
, it is also the maximum of
. If
, then
has no maximum.