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Theorem ceqex 2647
 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 1466 . . 3 (x = Ax x = A)
2 isset 2538 . . 3 (A V ↔ x x = A)
31, 2sylibr 137 . 2 (x = AA V)
4 eqeq2 2032 . . . 4 (y = A → (x = yx = A))
54anbi1d 441 . . . . . 6 (y = A → ((x = y φ) ↔ (x = A φ)))
65exbidv 1689 . . . . 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 1466 . . . . 5 ((x = y φ) → x(x = y φ))
109ex 108 . . . 4 (x = y → (φx(x = y φ)))
11 vex 2537 . . . . . 6 y V
1211alexeq 2646 . . . . 5 (x(x = yφ) ↔ x(x = y φ))
13 sp 1384 . . . . . 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 2589 . 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 1315  ∃wex 1362   = wceq 1374   ∈ wcel 1376  Vcvv 2534 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 617  ax-5 1316  ax-7 1317  ax-gen 1318  ax-ie1 1363  ax-ie2 1364  ax-8 1378  ax-10 1379  ax-11 1380  ax-i12 1381  ax-bnd 1382  ax-4 1383  ax-17 1402  ax-i9 1406  ax-ial 1411  ax-i5r 1412  ax-ext 2005 This theorem depends on definitions:  df-bi 110  df-tru 1232  df-nf 1330  df-sb 1629  df-clab 2010  df-cleq 2016  df-clel 2019  df-nfc 2150  df-v 2536 This theorem is referenced by:  ceqsexg  2648  sbc6g  2764
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