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Theorem uniss 3628
Description: Subclass relationship for class union. Theorem 61 of [Suppes] p. 39. (Contributed by NM, 22-Mar-1998.) (Proof shortened by Andrew Salmon, 29-Jun-2011.)
Assertion
Ref Expression
uniss (𝐴𝐵 𝐴 𝐵)

Proof of Theorem uniss
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 ssel 2966 . . . . 5 (𝐴𝐵 → (𝑦𝐴𝑦𝐵))
21anim2d 324 . . . 4 (𝐴𝐵 → ((𝑥𝑦𝑦𝐴) → (𝑥𝑦𝑦𝐵)))
32eximdv 1776 . . 3 (𝐴𝐵 → (∃𝑦(𝑥𝑦𝑦𝐴) → ∃𝑦(𝑥𝑦𝑦𝐵)))
4 eluni 3610 . . 3 (𝑥 𝐴 ↔ ∃𝑦(𝑥𝑦𝑦𝐴))
5 eluni 3610 . . 3 (𝑥 𝐵 ↔ ∃𝑦(𝑥𝑦𝑦𝐵))
63, 4, 53imtr4g 198 . 2 (𝐴𝐵 → (𝑥 𝐴𝑥 𝐵))
76ssrdv 2978 1 (𝐴𝐵 𝐴 𝐵)
Colors of variables: wff set class
Syntax hints:  wi 4  wa 101  wex 1397  wcel 1409  wss 2944   cuni 3607
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-io 640  ax-5 1352  ax-7 1353  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-8 1411  ax-10 1412  ax-11 1413  ax-i12 1414  ax-bndl 1415  ax-4 1416  ax-17 1435  ax-i9 1439  ax-ial 1443  ax-i5r 1444  ax-ext 2038
This theorem depends on definitions:  df-bi 114  df-tru 1262  df-nf 1366  df-sb 1662  df-clab 2043  df-cleq 2049  df-clel 2052  df-nfc 2183  df-v 2576  df-in 2951  df-ss 2958  df-uni 3608
This theorem is referenced by:  unissi  3630  unissd  3631  intssuni2m  3666  relfld  4873
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