Metamath Proof Explorer


Theorem ineq1d

Description: Equality deduction for intersection of two classes. (Contributed by NM, 10-Apr-1994)

Ref Expression
Hypothesis ineq1d.1 ⊢ φ → A = B
Assertion ineq1d ⊢ φ → A ∩ C = B ∩ C

Proof

Step Hyp Ref Expression
1 ineq1d.1 ⊢ φ → A = B
2 ineq1 ⊢ A = B → A ∩ C = B ∩ C
3 1 2 syl ⊢ φ → A ∩ C = B ∩ C