Supremum is the least upper bound

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SUMMARY

The discussion centers on the mathematical proof that the supremum of a set is the least upper bound. The proof establishes that if x is an upper bound of a set S, then x must be greater than or equal to the supremum of S. It further clarifies that if there exists an upper bound y that is less than or equal to the supremum, it leads to a contradiction, confirming that the supremum is indeed the least upper bound. Participants also discuss the definitions of "supremum" and "least upper bound," asserting their equivalence.

PREREQUISITES
  • Understanding of set theory and upper bounds
  • Familiarity with the concept of supremum in real analysis
  • Basic knowledge of mathematical proofs and contradiction
  • Definitions of key terms: supremum and least upper bound
NEXT STEPS
  • Study the properties of supremum in real analysis
  • Explore examples of sets with different supremums
  • Learn about the completeness property of real numbers
  • Investigate the implications of upper bounds in optimization problems
USEFUL FOR

Mathematics students, educators, and anyone interested in real analysis, particularly those studying properties of sets and bounds.

sara_87
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Homework Statement



Prove that the supremum is the least upper bound

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The Attempt at a Solution



Proof: let x be an upper bound of a set S then x>=supS (by definition). If there exists an upper bound y and y<=SupS then y is not an upper bound (contradiction) therefore every upper bound is greater than SupS so SupS is the least upper bound.

Is that proof correct?

Thank you.
 
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Please tell what your definitions of "supremum" and "least upper bound" are! As far as I know "supremum" is just another name for "least upper bound" and there is nothing to prove.
 

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