Theorem neleqtrd 2448

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	⊢ (φ → ¬ C ∈ A)
neleqtrd.2	⊢ (φ → A = B)

Assertion

Ref	Expression
neleqtrd	⊢ (φ → ¬ C ∈ B)

Proof of Theorem neleqtrd

Step	Hyp	Ref	Expression
1		neleqtrd.1	. 2 ⊢ (φ → ¬ C ∈ A)
2		neleqtrd.2	. . 3 ⊢ (φ → A = B)
3	2	eleq2d 2420	. 2 ⊢ (φ → (C ∈ A ↔ C ∈ B))
4	1, 3	mtbid 291	1 ⊢ (φ → ¬ C ∈ B)

Syntax hints:  ¬ wn 3   → wi 4   = wceq 1642   ∈ wcel 1710

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-11 1746  ax-ext 2334

This theorem depends on definitions:  df-bi 177  df-an 360  df-ex 1542  df-cleq 2346  df-clel 2349

This theorem is referenced by: (None)