Theorem neleqtrd 2237

Description: If a class is not an element of another class, it is also not an element of an equal class. Deduction form. (Contributed by David Moews, 1-May-2017.)

Hypotheses

Ref	Expression
neleqtrd.1	|- ( ph -> -. C e. A )
neleqtrd.2	|- ( ph -> A = B )

Assertion

Ref	Expression
neleqtrd	|- ( ph -> -. C e. B )

Proof of Theorem neleqtrd

Step	Hyp	Ref	Expression
1		neleqtrd.1	. 2 |- ( ph -> -. C e. A )
2		neleqtrd.2	. . 3 |- ( ph -> A = B )
3	2	eleq2d 2209	. 2 |- ( ph -> ( C e. A <-> C e. B ) )
4	1, 3	mtbid 661	1 |- ( ph -> -. C e. B )

Syntax hints:   -. wn 3   -> wi 4   = wceq 1331   e. wcel 1480

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 603  ax-in2 604  ax-5 1423  ax-gen 1425  ax-ie1 1469  ax-ie2 1470  ax-4 1487  ax-17 1506  ax-ial 1514  ax-ext 2121

This theorem depends on definitions:  df-bi 116  df-cleq 2132  df-clel 2135

This theorem is referenced by: (None)