Theorem sseqtrdi 3195

Description: A chained subclass and equality deduction. (Contributed by NM, 25-Apr-2004.)

Hypotheses

Ref	Expression
sseqtrdi.1	|- ( ph -> A C_ B )
sseqtrdi.2	|- B = C

Assertion

Ref	Expression
sseqtrdi	|- ( ph -> A C_ C )

Proof of Theorem sseqtrdi

Step	Hyp	Ref	Expression
1		sseqtrdi.1	. 2 |- ( ph -> A C_ B )
2		sseqtrdi.2	. . 3 |- B = C
3	2	sseq2i 3174	. 2 |- ( A C_ B <-> A C_ C )
4	1, 3	sylib 121	1 |- ( ph -> A C_ C )

Syntax hints:   -> wi 4   = wceq 1348   C_ wss 3121

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-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-11 1499  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-nf 1454  df-sb 1756  df-clab 2157  df-cleq 2163  df-clel 2166  df-in 3127  df-ss 3134

This theorem is referenced by:  sseqtrrdi  3196  onintonm  4501  relrelss  5137  iotanul  5175  foimacnv  5460  cauappcvgprlemladdru  7618  zsumdc  11347  fsum3cvg3  11359  zproddc  11542  nninfdcex  11908  zsupssdc  11909  distop  12879  cnptoprest  13033  pwle2  14031  pw1nct  14036