Theorem sselii 3139

Description: Membership inference from subclass relationship. (Contributed by NM, 31-May-1999.)

Hypotheses

Ref	Expression
sseli.1	⊢ 𝐴 ⊆ 𝐵
sselii.2	⊢ 𝐶 ∈ 𝐴

Assertion

Ref	Expression
sselii	⊢ 𝐶 ∈ 𝐵

Proof of Theorem sselii

Step	Hyp	Ref	Expression
1		sselii.2	. 2 ⊢ 𝐶 ∈ 𝐴
2		sseli.1	. . 3 ⊢ 𝐴 ⊆ 𝐵
3	2	sseli 3138	. 2 ⊢ (𝐶 ∈ 𝐴 → 𝐶 ∈ 𝐵)
4	1, 3	ax-mp 5	1 ⊢ 𝐶 ∈ 𝐵

Syntax hints:   ∈ wcel 2136   ⊆ wss 3116

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-11 1494  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-nf 1449  df-sb 1751  df-clab 2152  df-cleq 2158  df-clel 2161  df-in 3122  df-ss 3129

This theorem is referenced by:  brtpos0  6220  ax1cn  7802  recni  7911  0xr  7945  pnfxr  7951  nn0rei  9125  0xnn0  9183  nnzi  9212  nn0zi  9213  lgsdir2lem3  13571