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ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Power Sets
Relations
imaeq1d
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imaeq2d
Metamath Proof Explorer
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Theorem
imaeq1d
Description:
Equality theorem for image.
(Contributed by
FL
, 15-Dec-2006)
Ref
Expression
Hypothesis
imaeq1d.1
⊢
φ
→
A
=
B
Assertion
imaeq1d
⊢
φ
→
A
C
=
B
C
Proof
Step
Hyp
Ref
Expression
1
imaeq1d.1
⊢
φ
→
A
=
B
2
imaeq1
⊢
A
=
B
→
A
C
=
B
C
3
1
2
syl
⊢
φ
→
A
C
=
B
C