Theorem eqsstr3d 1535

Description: Substitution of equality into a subclass relationship.

Hypotheses

Ref	Expression
eqsstr3d.1	|- (ph -> B = A)
eqsstr3d.2	|- (ph -> B (_ C)

Assertion

Ref	Expression
eqsstr3d	|- (ph -> A (_ C)

Proof of Theorem eqsstr3d

Step	Hyp	Ref	Expression
1		eqsstr3d.1	. . 3 |- (ph -> B = A)
2	1	cleqcomd 1106	. 2 |- (ph -> A = B)
3		eqsstr3d.2	. 2 |- (ph -> B (_ C)
4	2, 3	eqsstrd 1534	1 |- (ph -> A (_ C)

Syntax hints:   -> wi 2   = wceq 1091   (_ wss 1487

This theorem is referenced by:  oaword1 3154  nnmordi 3188  r1val1 3502  sh1dle 5748  sumdmdi 5785  sumdmd 5787

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-6 675  ax-7 676  ax-gen 677  ax-8 798  ax-9 799  ax-10 800  ax-11 801  ax-12 802  ax-16 922  ax-17 925  ax-ext 1074

This theorem depends on definitions:  df-bi 128  df-an 198  df-ex 679  df-sb 853  df-clab 1093  df-cleq 1097  df-clel 1099  df-in 1491  df-ss 1492

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