Theorem anbi2 688

Description: Introduce a left conjunct to both sides of a logical equivalence. (Contributed by NM, 16-Nov-2013.)

Assertion

Ref	Expression
anbi2	|- ((ph <-> ps) -> ((ch /\ ph) <-> (ch /\ ps)))

Proof of Theorem anbi2

Step	Hyp	Ref	Expression
1		id 19	. 2 |- ((ph <-> ps) -> (ph <-> ps))
2	1	anbi2d 684	1 |- ((ph <-> ps) -> ((ch /\ ph) <-> (ch /\ ps)))

Syntax hints:   -> wi 4   <-> wb 176   /\ wa 358

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 177  df-an 360

This theorem is referenced by: (None)