Theorem sseq1i 3209

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 3206	. 2 ⊢ (𝐴 = 𝐵 → (𝐴 ⊆ 𝐶 ↔ 𝐵 ⊆ 𝐶))
3	1, 2	ax-mp 5	1 ⊢ (𝐴 ⊆ 𝐶 ↔ 𝐵 ⊆ 𝐶)

Syntax hints:   ↔ wb 105   = wceq 1364   ⊆ wss 3157

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 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-11 1520  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-in 3163  df-ss 3170

This theorem is referenced by:  eqsstri  3215  eqsstrid  3229  ssab  3253  rabss  3260  uniiunlem  3272  prss  3778  prssg  3779  tpss  3788  iunss  3957  pwtr  4252  ordsucss  4540  elomssom  4641  cores2  5182  dffun2  5268  funimaexglem  5341  idref  5803  ordgt0ge1  6493  3nsssucpw1  7303  prarloclemn  7566  bdeqsuc  15527  bj-omssind  15581