Theorem nsyl3 627

Description: A negated syllogism inference. (Contributed by NM, 1-Dec-1995.) (Revised by NM, 13-Jun-2013.)

Hypotheses

Ref	Expression
nsyl3.1	⊢ (𝜑 → ¬ 𝜓)
nsyl3.2	⊢ (𝜒 → 𝜓)

Assertion

Ref	Expression
nsyl3	⊢ (𝜒 → ¬ 𝜑)

Proof of Theorem nsyl3

Step	Hyp	Ref	Expression
1		nsyl3.2	. 2 ⊢ (𝜒 → 𝜓)
2		nsyl3.1	. . 3 ⊢ (𝜑 → ¬ 𝜓)
3	2	a1i 9	. 2 ⊢ (𝜒 → (𝜑 → ¬ 𝜓))
4	1, 3	mt2d 626	1 ⊢ (𝜒 → ¬ 𝜑)

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:  con2i  628  nsyl  629  pm2.65i  640  cesare  2146  cesaro  2150  pwnss  4188  sucprcreg  4581  reg3exmidlemwe  4611  reldmtpos  6306  snexxph  7009  elfi2  7031  ismkvnex  7214  fzn  10108  seq3f1olemqsum  10584  pcmpt2  12482  elply2  14881