Metamath Proof Explorer


Theorem coeq2i

Description: Equality inference for composition of two classes. (Contributed by NM, 16-Nov-2000)

Ref Expression
Hypothesis coeq1i.1 A = B
Assertion coeq2i C A = C B

Proof

Step Hyp Ref Expression
1 coeq1i.1 A = B
2 coeq2 A = B C A = C B
3 1 2 ax-mp C A = C B