Metamath Proof Explorer


Theorem ovif

Description: Move a conditional outside of an operation. (Contributed by Thierry Arnoux, 25-Jan-2017)

Ref Expression
Assertion ovif ⊢ if φ A B F C = if φ A F C B F C

Proof

Step Hyp Ref Expression
1 oveq1 ⊢ if φ A B = A → if φ A B F C = A F C
2 oveq1 ⊢ if φ A B = B → if φ A B F C = B F C
3 1 2 ifsb ⊢ if φ A B F C = if φ A F C B F C