Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Power Sets
Functions
funeqd
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nffun
Metamath Proof Explorer
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Theorem
funeqd
Description:
Equality deduction for the function predicate.
(Contributed by
NM
, 23-Feb-2013)
Ref
Expression
Hypothesis
funeqd.1
⊢
φ
→
A
=
B
Assertion
funeqd
⊢
φ
→
Fun
⁡
A
↔
Fun
⁡
B
Proof
Step
Hyp
Ref
Expression
1
funeqd.1
⊢
φ
→
A
=
B
2
funeq
⊢
A
=
B
→
Fun
⁡
A
↔
Fun
⁡
B
3
1
2
syl
⊢
φ
→
Fun
⁡
A
↔
Fun
⁡
B