Theorem psseq12i 1563

Description: An equality inference for the proper subclass relationship.

Hypotheses

Ref	Expression
psseq1i.1	|- A = B
psseq12i.2	|- C = D

Assertion

Ref	Expression
psseq12i	|- (A (. C <-> B (. D)

Proof of Theorem psseq12i

Step	Hyp	Ref	Expression
1		psseq1i.1	. . 3 |- A = B
2	1	psseq1i 1561	. 2 |- (A (. C <-> B (. C)
3		psseq12i.2	. . 3 |- C = D
4	3	psseq2i 1562	. 2 |- (B (. C <-> B (. D)
5	2, 4	bitr 151	1 |- (A (. C <-> B (. D)

Syntax hints:   <-> wb 127   = wceq 1091   (. wpss 1488

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-ne 1192  df-in 1491  df-ss 1492  df-pss 1494

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