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ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Union
Equinumerosity
ensymi
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ensymd
Metamath Proof Explorer
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Theorem
ensymi
Description:
Symmetry of equinumerosity. Theorem 2 of
Suppes
p. 92.
(Contributed by
NM
, 25-Sep-2004)
Ref
Expression
Hypothesis
ensymi.2
⊢
A
≈
B
Assertion
ensymi
⊢
B
≈
A
Proof
Step
Hyp
Ref
Expression
1
ensymi.2
⊢
A
≈
B
2
ensym
⊢
A
≈
B
→
B
≈
A
3
1
2
ax-mp
⊢
B
≈
A