Theorem ninba 575

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 566	. 2 |- (-. ps -> ((ch /\ ps) <-> -. ph))
3	2	bicomd 399	1 |- (-. ps -> (-. ph <-> (ch /\ ps)))

Syntax hints:  -. wn 1   -> wi 2   <-> wb 127   /\ wa 196

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

This theorem depends on definitions:  df-bi 128  df-an 198

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