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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