Theorem sseq1i 3023

Description: An equality inference for the subclass relationship. (Contributed by NM, 18-Aug-1993.)

Hypothesis

Ref	Expression
sseq1i.1	⊢ 𝐴 = 𝐵

Assertion

Ref	Expression
sseq1i	⊢ (𝐴 ⊆ 𝐶 ↔ 𝐵 ⊆ 𝐶)

Proof of Theorem sseq1i

Step	Hyp	Ref	Expression
1		sseq1i.1	. 2 ⊢ 𝐴 = 𝐵
2		sseq1 3020	. 2 ⊢ (𝐴 = 𝐵 → (𝐴 ⊆ 𝐶 ↔ 𝐵 ⊆ 𝐶))
3	1, 2	ax-mp 7	1 ⊢ (𝐴 ⊆ 𝐶 ↔ 𝐵 ⊆ 𝐶)

Syntax hints:   ↔ wb 103   = wceq 1284   ⊆ wss 2973

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-5 1376  ax-7 1377  ax-gen 1378  ax-ie1 1422  ax-ie2 1423  ax-8 1435  ax-11 1437  ax-4 1440  ax-17 1459  ax-i9 1463  ax-ial 1467  ax-i5r 1468  ax-ext 2063

This theorem depends on definitions:  df-bi 115  df-nf 1390  df-sb 1686  df-clab 2068  df-cleq 2074  df-clel 2077  df-in 2979  df-ss 2986

This theorem is referenced by:  eqsstri  3029  syl5eqss  3043  ssab  3064  rabss  3071  uniiunlem  3082  prss  3541  prssg  3542  tpss  3550  iunss  3719  pwtr  3974  ordsucss  4248  elnn  4346  cores2  4853  dffun2  4932  funimaexglem  5002  idref  5417  ordgt0ge1  6041  prarloclemn  6689  bdeqsuc  10672  bj-omssind  10730