Theorem pm2.21ddne 2591

Description: A contradiction implies anything. Equality/inequality deduction form. (Contributed by David Moews, 28-Feb-2017.)

Hypotheses

Ref	Expression
pm2.21ddne.1	|- (ph -> A = B)
pm2.21ddne.2	|- (ph -> A =/= B)

Assertion

Ref	Expression
pm2.21ddne	|- (ph -> ps)

Proof of Theorem pm2.21ddne

Step	Hyp	Ref	Expression
1		pm2.21ddne.1	. 2 |- (ph -> A = B)
2		pm2.21ddne.2	. . 3 |- (ph -> A =/= B)
3	2	neneqd 2533	. 2 |- (ph -> -. A = B)
4	1, 3	pm2.21dd 99	1 |- (ph -> ps)

This proof depends on syntax axioms:   -> wi 4   = wceq 1642   =/= wne 2517

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 177  df-ne 2519

This theorem is used by: (None)