Theorem pm2.65i 640

Description: Inference for proof by contradiction. (Contributed by NM, 18-May-1994.) (Proof shortened by Wolf Lammen, 11-Sep-2013.)

Hypotheses

Ref	Expression
pm2.65i.1	|- ( ph -> ps )
pm2.65i.2	|- ( ph -> -. ps )

Assertion

Ref	Expression
pm2.65i	|- -. ph

Proof of Theorem pm2.65i

Step	Hyp	Ref	Expression
1		pm2.65i.2	. . 3 |- ( ph -> -. ps )
2		pm2.65i.1	. . 3 |- ( ph -> ps )
3	1, 2	nsyl3 627	. 2 |- ( ph -> -. ph )
4		pm2.01 617	. 2 |- ( ( ph -> -. ph ) -> -. ph )
5	3, 4	ax-mp 5	1 |- -. ph

Syntax hints:   -. wn 3   -> wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-in1 615  ax-in2 616

This theorem is referenced by:  mt2  641  mto  663  pm5.19  707  noel  3463  0nelop  4291  elirr  4588  en2lp  4601  soirri  5076  canth  5896  0neqopab  5989  fzp1disj  10201  fzonel  10282  fzouzdisj  10302  4sqlem17  12672  lgsval2lem  15429  bj-imnimnn  15607  nnnotnotr  15859