Theorem

Cantor-Schroder-Bernstein Theorem

Logic and Foundations

If there is an injective function from set A into set B and an injective function from set B into set A, then there is a bijection between A and B. Named for Georg Cantor, Felix Bernstein and Ernst Schroder, it is a fundamental tool for comparing the sizes of infinite sets.

Facts
Statement
If there is an injective function from set A into set B and an injective function from set B into set A, then there exists a bijection between A and B, so the two sets have the same cardinality. 2
Proof Year
1897 2
Cantor stated the theorem without proof in 1887; Dedekind proved it independently the same year but never published his proof; the earliest proof publicly presented was Bernstein's, given in Cantor's seminar in 1897 (published 1898); Schroder announced an independent proof in 1896, published 1898, later shown to be flawed.
Classification
Statement Form
Existence Theorem 1
Connections

Associated With

Has Statement Form

In Branch

Principal Result Of

Source Ernst Schröder (mathematician) (Wikipedia)
Source Felix Bernstein (MacTutor)

Proved By

Sources
1. Wikipedia: Schröder-Bernstein theorem
WikipediaLead section, statement-form reference
Quote, Lead section, statement-form reference
In set theory, the Schröder-Bernstein theorem states that, if there exist injective functions f : A → B and g : B → A between the sets A and B, then there exists a bijective function h : A → B.
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2. Cantor-Schroder-Bernstein theorem (Wikipedia)
Wikimedia Foundation
  • Introduction
    the Schröder-Bernstein theorem states that, if there exist injective functions f : A → B and g : B → A between the sets A and B, then there exists a bijective function h : A → B
  • History section, 1897 entry
    Bernstein, a 19-year-old student in Cantor's Seminar, presents his proof.
  • In Group: Set Theory, Lead section
    In set theory, the Schröder-Bernstein theorem states that
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Ernst Schröder (mathematician) (Wikipedia)
Principal Result Of: Ernst Schröder (mathematician), Work
Quote, Principal Result Of: Ernst Schröder (mathematician), Work
he codiscovered the Cantor-Bernstein-Schröder theorem
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Felix Bernstein (MacTutor)
Principal Result Of: Felix Bernstein (mathematician), Summary
Quote, Principal Result Of: Felix Bernstein (mathematician), Summary
Felix Bernstein established his famous theorem on the equivalence of sets while in Cantor's seminar at Halle in 1897.
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