Theorem ssiun2 5047

Description: Identity law for subset of an indexed union. (Contributed by NM, 12-Oct-2003.) (Proof shortened by Andrew Salmon, 25-Jul-2011.)

Assertion

Ref	Expression
ssiun2	⊢ (𝑥 ∈ 𝐴 → 𝐵 ⊆ ∪ 𝑥 ∈ 𝐴 𝐵)

Proof of Theorem ssiun2

Dummy variable 𝑦 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		rspe 3249	. . . 4 ⊢ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) → ∃𝑥 ∈ 𝐴 𝑦 ∈ 𝐵)
2	1	ex 412	. . 3 ⊢ (𝑥 ∈ 𝐴 → (𝑦 ∈ 𝐵 → ∃𝑥 ∈ 𝐴 𝑦 ∈ 𝐵))
3		eliun 4995	. . 3 ⊢ (𝑦 ∈ ∪ 𝑥 ∈ 𝐴 𝐵 ↔ ∃𝑥 ∈ 𝐴 𝑦 ∈ 𝐵)
4	2, 3	imbitrrdi 252	. 2 ⊢ (𝑥 ∈ 𝐴 → (𝑦 ∈ 𝐵 → 𝑦 ∈ ∪ 𝑥 ∈ 𝐴 𝐵))
5	4	ssrdv 3989	1 ⊢ (𝑥 ∈ 𝐴 → 𝐵 ⊆ ∪ 𝑥 ∈ 𝐴 𝐵)

Syntax hints:   → wi 4   ∈ wcel 2108  ∃wrex 3070   ⊆ wss 3951  ∪ ciun 4991

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2007  ax-8 2110  ax-9 2118  ax-12 2177  ax-ext 2708

This theorem depends on definitions:  df-bi 207  df-an 396  df-tru 1543  df-ex 1780  df-sb 2065  df-clab 2715  df-cleq 2729  df-clel 2816  df-rex 3071  df-v 3482  df-ss 3968  df-iun 4993

This theorem is referenced by:  ssiun2s  5048  disjxiun  5140  triun  5274  iunopeqop  5526  ixpf  8960  ixpiunwdom  9630  r1sdom  9814  r1val1  9826  rankuni2b  9893  rankval4  9907  cplem1  9929  domtriomlem  10482  ac6num  10519  iunfo  10579  iundom2g  10580  pwfseqlem3  10700  inar1  10815  tskuni  10823  iunconnlem  23435  ptclsg  23623  ovoliunlem1  25537  limciun  25929  ssiun2sf  32572  iunxpssiun1  32581  djussxp2  32658  suppovss  32690  bnj906  34944  bnj999  34972  bnj1014  34975  bnj1408  35050  rdgssun  37379  cpcolld  44277  iunmapss  45220  ssmapsn  45221  sge0iunmpt  46433  sge0iun  46434  voliunsge0lem  46487  omeiunltfirp  46534