Theorem 3sstr4g 3196

Description: Substitution of equality into both sides of a subclass relationship. (Contributed by NM, 16-Aug-1994.) (Proof shortened by Eric Schmidt, 26-Jan-2007.)

Hypotheses

Ref	Expression
3sstr4g.1	⊢ (𝜑 → 𝐴 ⊆ 𝐵)
3sstr4g.2	⊢ 𝐶 = 𝐴
3sstr4g.3	⊢ 𝐷 = 𝐵

Assertion

Ref	Expression
3sstr4g	⊢ (𝜑 → 𝐶 ⊆ 𝐷)

Proof of Theorem 3sstr4g

Step	Hyp	Ref	Expression
1		3sstr4g.1	. 2 ⊢ (𝜑 → 𝐴 ⊆ 𝐵)
2		3sstr4g.2	. . 3 ⊢ 𝐶 = 𝐴
3		3sstr4g.3	. . 3 ⊢ 𝐷 = 𝐵
4	2, 3	sseq12i 3181	. 2 ⊢ (𝐶 ⊆ 𝐷 ↔ 𝐴 ⊆ 𝐵)
5	1, 4	sylibr 134	1 ⊢ (𝜑 → 𝐶 ⊆ 𝐷)

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:  rabss2  3236  unss2  3304  sslin  3359  ssopab2  4269  xpss12  4727  coss1  4775  coss2  4776  cnvss  4793  rnss  4850  ssres  4926  ssres2  4927  imass1  4996  imass2  4997  imadif  5288  imain  5290  ssoprab2  5921  suppssfv  6069  suppssov1  6070  tposss  6237  ss2ixp  6701  isumsplit  11467  isumrpcl  11470