Theorem ninba 768

Description: Miscellaneous inference relating falsehoods.

Hypothesis

Ref	Expression
ninba.1	|- ph

Assertion

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

Proof of Theorem ninba

Step	Hyp	Ref	Expression
1		ninba.1	. . 3 |- ph
2	1	niabn 758	. 2 |- (-. ps -> ((ch /\ ps) <-> -. ph))
3	2	bicomd 520	1 |- (-. ps -> (-. ph <-> (ch /\ ps)))

Syntax hints:  -. wn 2   -> wi 3   <-> wb 146   /\ wa 223

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7

This theorem depends on definitions:  df-bi 147  df-an 225

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