Theorem necon1addc 2358

Description: Contrapositive deduction for inequality. (Contributed by Jim Kingdon, 19-May-2018.)

Hypothesis

Ref	Expression
necon1addc.1	|- ( ph -> (DECID ps -> ( -. ps -> A = B ) ) )

Assertion

Ref	Expression
necon1addc	|- ( ph -> (DECID ps -> ( A =/= B -> ps ) ) )

Proof of Theorem necon1addc

Step	Hyp	Ref	Expression
1		df-ne 2283	. 2 |- ( A =/= B <-> -. A = B )
2		necon1addc.1	. . 3 |- ( ph -> (DECID ps -> ( -. ps -> A = B ) ) )
3		con1dc 824	. . 3 |- (DECID ps -> ( ( -. ps -> A = B ) -> ( -. A = B -> ps ) ) )
4	2, 3	sylcom 28	. 2 |- ( ph -> (DECID ps -> ( -. A = B -> ps ) ) )
5	1, 4	syl7bi 164	1 |- ( ph -> (DECID ps -> ( A =/= B -> ps ) ) )

Syntax hints:   -. wn 3   -> wi 4  DECID wdc 802   = wceq 1314   =/= wne 2282

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 586  ax-in2 587  ax-io 681

This theorem depends on definitions:  df-bi 116  df-stab 799  df-dc 803  df-ne 2283

This theorem is referenced by: (None)