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Theorem r19.2z 2337
Description: Theorem 19.2 of [Margaris] p. 89 with restricted quantifiers (compare 19.2 1026). The restricted version is valid only when the domain of quantification is not empty.
Assertion
Ref Expression
r19.2z |- ((A =/= (/) /\ A.x e. A ph) -> E.x e. A ph)
Distinct variable group:   x,A

Proof of Theorem r19.2z
StepHypRef Expression
1 df-ral 1641 . . . 4 |- (A.x e. A ph <-> A.x(x e. A -> ph))
2 exintr 1113 . . . 4 |- (A.x(x e. A -> ph) -> (E.x x e. A -> E.x(x e. A /\ ph)))
31, 2sylbi 199 . . 3 |- (A.x e. A ph -> (E.x x e. A -> E.x(x e. A /\ ph)))
4 ne0 2278 . . 3 |- (A =/= (/) <-> E.x x e. A)
5 df-rex 1642 . . 3 |- (E.x e. A ph <-> E.x(x e. A /\ ph))
63, 4, 53imtr4g 551 . 2 |- (A.x e. A ph -> (A =/= (/) -> E.x e. A ph))
76impcom 351 1 |- ((A =/= (/) /\ A.x e. A ph) -> E.x e. A ph)
Colors of variables: wff set class
Syntax hints:   -> wi 3   /\ wa 223  A.wal 951   e. wcel 955  E.wex 977   =/= wne 1577  A.wral 1637  E.wrex 1638  (/)c0 2270
This theorem is referenced by:  intssuni 2545  alephval2 4874  cfeq0 4886  cfsuc 4887  isgrp2i 8011  fgsb 10444  fgsb2 10449
This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7  ax-7 959  ax-gen 960  ax-8 961  ax-10 963  ax-12 965  ax-17 968  ax-4 970  ax-5o 972  ax-6o 975  ax-9o 1119  ax-10o 1136  ax-16 1206  ax-11o 1213  ax-ext 1452
This theorem depends on definitions:  df-bi 147  df-or 224  df-an 225  df-ex 978  df-sb 1168  df-clab 1457  df-cleq 1462  df-clel 1465  df-ne 1579  df-ral 1641  df-rex 1642  df-v 1803  df-dif 2039  df-nul 2271
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