Theorem sseqtrdi 3245

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 3224	. 2 ⊢ (𝐴 ⊆ 𝐵 ↔ 𝐴 ⊆ 𝐶)
4	1, 3	sylib 122	1 ⊢ (𝜑 → 𝐴 ⊆ 𝐶)

Syntax hints:   → wi 4   = wceq 1373   ⊆ wss 3170

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 1471  ax-7 1472  ax-gen 1473  ax-ie1 1517  ax-ie2 1518  ax-8 1528  ax-11 1530  ax-4 1534  ax-17 1550  ax-i9 1554  ax-ial 1558  ax-i5r 1559  ax-ext 2188

This theorem depends on definitions:  df-bi 117  df-nf 1485  df-sb 1787  df-clab 2193  df-cleq 2199  df-clel 2202  df-in 3176  df-ss 3183

This theorem is referenced by:  sseqtrrdi  3246  onintonm  4573  relrelss  5218  iotanul  5256  foimacnv  5552  pw1m  7355  cauappcvgprlemladdru  7789  nninfdcex  10402  zsupssdc  10403  zsumdc  11770  fsum3cvg3  11782  zproddc  11965  imasaddfnlemg  13221  sraring  14286  distop  14632  cnptoprest  14786  upgr1edc  15789  pwle2  16076  pw1nct  16081