Theorem unssd 3148

Description: A deduction showing the union of two subclasses is a subclass. (Contributed by Jonathan Ben-Naim, 3-Jun-2011.)

Hypotheses

Ref	Expression
unssd.1	⊢ (𝜑 → 𝐴 ⊆ 𝐶)
unssd.2	⊢ (𝜑 → 𝐵 ⊆ 𝐶)

Assertion

Ref	Expression
unssd	⊢ (𝜑 → (𝐴 ∪ 𝐵) ⊆ 𝐶)

Proof of Theorem unssd

Step	Hyp	Ref	Expression
1		unssd.1	. 2 ⊢ (𝜑 → 𝐴 ⊆ 𝐶)
2		unssd.2	. 2 ⊢ (𝜑 → 𝐵 ⊆ 𝐶)
3		unss 3146	. . 3 ⊢ ((𝐴 ⊆ 𝐶 ∧ 𝐵 ⊆ 𝐶) ↔ (𝐴 ∪ 𝐵) ⊆ 𝐶)
4	3	biimpi 118	. 2 ⊢ ((𝐴 ⊆ 𝐶 ∧ 𝐵 ⊆ 𝐶) → (𝐴 ∪ 𝐵) ⊆ 𝐶)
5	1, 2, 4	syl2anc 403	1 ⊢ (𝜑 → (𝐴 ∪ 𝐵) ⊆ 𝐶)

Syntax hints:   → wi 4   ∧ wa 102   ∪ cun 2971   ⊆ 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-io 662  ax-5 1376  ax-7 1377  ax-gen 1378  ax-ie1 1422  ax-ie2 1423  ax-8 1435  ax-10 1436  ax-11 1437  ax-i12 1438  ax-bndl 1439  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-tru 1287  df-nf 1390  df-sb 1686  df-clab 2068  df-cleq 2074  df-clel 2077  df-nfc 2208  df-v 2603  df-un 2977  df-in 2979  df-ss 2986

This theorem is referenced by:  tpssi  3551  un0addcl  8321  un0mulcl  8322  fzosplit  9186  fzouzsplit  9188  bj-omtrans  10751