Theorem sseqtrdi 3201

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

Hypotheses

Ref	Expression
sseqtrdi.1	⊢ (𝜑 → 𝐴 ⊆ 𝐵)
sseqtrdi.2	⊢ 𝐵 = 𝐶

Assertion

Ref	Expression
sseqtrdi	⊢ (𝜑 → 𝐴 ⊆ 𝐶)

Proof of Theorem sseqtrdi

Step	Hyp	Ref	Expression
1		sseqtrdi.1	. 2 ⊢ (𝜑 → 𝐴 ⊆ 𝐵)
2		sseqtrdi.2	. . 3 ⊢ 𝐵 = 𝐶
3	2	sseq2i 3180	. 2 ⊢ (𝐴 ⊆ 𝐵 ↔ 𝐴 ⊆ 𝐶)
4	1, 3	sylib 122	1 ⊢ (𝜑 → 𝐴 ⊆ 𝐶)

Syntax hints:   → wi 4   = wceq 1353   ⊆ wss 3127

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1445  ax-7 1446  ax-gen 1447  ax-ie1 1491  ax-ie2 1492  ax-8 1502  ax-11 1504  ax-4 1508  ax-17 1524  ax-i9 1528  ax-ial 1532  ax-i5r 1533  ax-ext 2157

This theorem depends on definitions:  df-bi 117  df-nf 1459  df-sb 1761  df-clab 2162  df-cleq 2168  df-clel 2171  df-in 3133  df-ss 3140

This theorem is referenced by:  sseqtrrdi  3202  onintonm  4510  relrelss  5147  iotanul  5185  foimacnv  5471  cauappcvgprlemladdru  7630  zsumdc  11360  fsum3cvg3  11372  zproddc  11555  nninfdcex  11921  zsupssdc  11922  distop  13165  cnptoprest  13319  pwle2  14317  pw1nct  14322