Theorem sseqtrdi 3205

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 3184	. 2 ⊢ (𝐴 ⊆ 𝐵 ↔ 𝐴 ⊆ 𝐶)
4	1, 3	sylib 122	1 ⊢ (𝜑 → 𝐴 ⊆ 𝐶)

Syntax hints:   → wi 4   = wceq 1353   ⊆ wss 3131

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 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-11 1506  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-ext 2159

This theorem depends on definitions:  df-bi 117  df-nf 1461  df-sb 1763  df-clab 2164  df-cleq 2170  df-clel 2173  df-in 3137  df-ss 3144

This theorem is referenced by:  sseqtrrdi  3206  onintonm  4518  relrelss  5157  iotanul  5195  foimacnv  5481  cauappcvgprlemladdru  7657  zsumdc  11394  fsum3cvg3  11406  zproddc  11589  nninfdcex  11956  zsupssdc  11957  imasaddfnlemg  12740  distop  13624  cnptoprest  13778  pwle2  14787  pw1nct  14791