Metamath Proof Explorer


Theorem ineq1i

Description: Equality inference for intersection of two classes. (Contributed by NM, 26-Dec-1993)

Ref Expression
Hypothesis ineq1i.1 ⊢ A = B
Assertion ineq1i ⊢ A ∩ C = B ∩ C

Proof

Step Hyp Ref Expression
1 ineq1i.1 ⊢ A = B
2 ineq1 ⊢ A = B → A ∩ C = B ∩ C
3 1 2 ax-mp ⊢ A ∩ C = B ∩ C