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Theorem ceqex 2665
Description: Equality implies equivalence with substitution. (Contributed by NM, 2-Mar-1995.)
Assertion
Ref Expression
ceqex (x = A → (φx(x = A φ)))
Distinct variable group:   x,A
Allowed substitution hint:   φ(x)

Proof of Theorem ceqex
Dummy variable y is distinct from all other variables.
StepHypRef Expression
1 19.8a 1479 . . 3 (x = Ax x = A)
2 isset 2555 . . 3 (A V ↔ x x = A)
31, 2sylibr 137 . 2 (x = AA V)
4 eqeq2 2046 . . . 4 (y = A → (x = yx = A))
54anbi1d 438 . . . . . 6 (y = A → ((x = y φ) ↔ (x = A φ)))
65exbidv 1703 . . . . 5 (y = A → (x(x = y φ) ↔ x(x = A φ)))
76bibi2d 221 . . . 4 (y = A → ((φx(x = y φ)) ↔ (φx(x = A φ))))
84, 7imbi12d 223 . . 3 (y = A → ((x = y → (φx(x = y φ))) ↔ (x = A → (φx(x = A φ)))))
9 19.8a 1479 . . . . 5 ((x = y φ) → x(x = y φ))
109ex 108 . . . 4 (x = y → (φx(x = y φ)))
11 vex 2554 . . . . . 6 y V
1211alexeq 2664 . . . . 5 (x(x = yφ) ↔ x(x = y φ))
13 sp 1398 . . . . . 6 (x(x = yφ) → (x = yφ))
1413com12 27 . . . . 5 (x = y → (x(x = yφ) → φ))
1512, 14syl5bir 142 . . . 4 (x = y → (x(x = y φ) → φ))
1610, 15impbid 120 . . 3 (x = y → (φx(x = y φ)))
178, 16vtoclg 2607 . 2 (A V → (x = A → (φx(x = A φ))))
183, 17mpcom 32 1 (x = A → (φx(x = A φ)))
Colors of variables: wff set class
Syntax hints:  wi 4   wa 97  wb 98  wal 1240   = wceq 1242  wex 1378   wcel 1390  Vcvv 2551
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-io 629  ax-5 1333  ax-7 1334  ax-gen 1335  ax-ie1 1379  ax-ie2 1380  ax-8 1392  ax-10 1393  ax-11 1394  ax-i12 1395  ax-bndl 1396  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-tru 1245  df-nf 1347  df-sb 1643  df-clab 2024  df-cleq 2030  df-clel 2033  df-nfc 2164  df-v 2553
This theorem is referenced by:  ceqsexg  2666  sbc6g  2782
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