Theorem bj-nnan 14573

Description: The double negation of a conjunction implies the conjunction of the double negations. (Contributed by BJ, 24-Nov-2023.)

Assertion

Ref	Expression
bj-nnan	|- ( -. -. ( ph /\ ps ) -> ( -. -. ph /\ -. -. ps ) )

Proof of Theorem bj-nnan

Step	Hyp	Ref	Expression
1		simpl 109	. . . 4 |- ( ( ph /\ ps ) -> ph )
2	1	con3i 632	. . 3 |- ( -. ph -> -. ( ph /\ ps ) )
3	2	con3i 632	. 2 |- ( -. -. ( ph /\ ps ) -> -. -. ph )
4		simpr 110	. . . 4 |- ( ( ph /\ ps ) -> ps )
5	4	con3i 632	. . 3 |- ( -. ps -> -. ( ph /\ ps ) )
6	5	con3i 632	. 2 |- ( -. -. ( ph /\ ps ) -> -. -. ps )
7	3, 6	jca 306	1 |- ( -. -. ( ph /\ ps ) -> ( -. -. ph /\ -. -. ps ) )

Syntax hints:   -. wn 3   -> wi 4   /\ wa 104

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 614  ax-in2 615

This theorem is referenced by:  bj-stan  14584  bj-stand  14585