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Theorem rexss 3001
Description: Restricted existential quantification on a subset in terms of superset. (Contributed by Stefan O'Rear, 3-Apr-2015.)
Assertion
Ref Expression
rexss (AB → (x A φx B (x A φ)))
Distinct variable groups:   x,A   x,B
Allowed substitution hint:   φ(x)

Proof of Theorem rexss
StepHypRef Expression
1 ssel 2933 . . . . 5 (AB → (x Ax B))
21pm4.71rd 374 . . . 4 (AB → (x A ↔ (x B x A)))
32anbi1d 438 . . 3 (AB → ((x A φ) ↔ ((x B x A) φ)))
4 anass 381 . . 3 (((x B x A) φ) ↔ (x B (x A φ)))
53, 4syl6bb 185 . 2 (AB → ((x A φ) ↔ (x B (x A φ))))
65rexbidv2 2323 1 (AB → (x A φx B (x A φ)))
Colors of variables: wff set class
Syntax hints:  wi 4   wa 97  wb 98   wcel 1390  wrex 2301  wss 2911
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-5 1333  ax-7 1334  ax-gen 1335  ax-ie1 1379  ax-ie2 1380  ax-8 1392  ax-11 1394  ax-4 1397  ax-17 1416  ax-i9 1420  ax-ial 1424  ax-i5r 1425  ax-ext 2019
This theorem depends on definitions:  df-bi 110  df-nf 1347  df-sb 1643  df-clab 2024  df-cleq 2030  df-clel 2033  df-rex 2306  df-in 2918  df-ss 2925
This theorem is referenced by:  1idprl  6566  1idpru  6567  ltexprlemm  6574
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