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Theorem dveeq2or 1694
 Description: Quantifier introduction when one pair of variables is distinct. Like dveeq2 1693 but connecting ∀xx = y by a disjunction rather than negation and implication makes the theorem stronger in intuitionistic logic. (Contributed by Jim Kingdon, 1-Feb-2018.)
Assertion
Ref Expression
dveeq2or (x x = y x z = y)
Distinct variable group:   x,z

Proof of Theorem dveeq2or
StepHypRef Expression
1 ax-i12 1395 . . . . . 6 (x x = z (x x = y x(z = yx z = y)))
2 orass 683 . . . . . 6 (((x x = z x x = y) x(z = yx z = y)) ↔ (x x = z (x x = y x(z = yx z = y))))
31, 2mpbir 134 . . . . 5 ((x x = z x x = y) x(z = yx z = y))
4 pm1.4 645 . . . . . 6 ((x x = z x x = y) → (x x = y x x = z))
54orim1i 676 . . . . 5 (((x x = z x x = y) x(z = yx z = y)) → ((x x = y x x = z) x(z = yx z = y)))
63, 5ax-mp 7 . . . 4 ((x x = y x x = z) x(z = yx z = y))
7 orass 683 . . . 4 (((x x = y x x = z) x(z = yx z = y)) ↔ (x x = y (x x = z x(z = yx z = y))))
86, 7mpbi 133 . . 3 (x x = y (x x = z x(z = yx z = y)))
9 ax16 1691 . . . . . 6 (x x = z → (z = yx z = y))
109a5i 1432 . . . . 5 (x x = zx(z = yx z = y))
11 id 19 . . . . 5 (x(z = yx z = y) → x(z = yx z = y))
1210, 11jaoi 635 . . . 4 ((x x = z x(z = yx z = y)) → x(z = yx z = y))
1312orim2i 677 . . 3 ((x x = y (x x = z x(z = yx z = y))) → (x x = y x(z = yx z = y)))
148, 13ax-mp 7 . 2 (x x = y x(z = yx z = y))
15 df-nf 1347 . . . 4 (Ⅎx z = yx(z = yx z = y))
1615biimpri 124 . . 3 (x(z = yx z = y) → Ⅎx z = y)
1716orim2i 677 . 2 ((x x = y x(z = yx z = y)) → (x x = y x z = y))
1814, 17ax-mp 7 1 (x x = y x z = y)
 Colors of variables: wff set class Syntax hints:   → wi 4   ∨ wo 628  ∀wal 1240  Ⅎwnf 1346 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-4 1397  ax-17 1416  ax-i9 1420  ax-ial 1424 This theorem depends on definitions:  df-bi 110  df-nf 1347  df-sb 1643 This theorem is referenced by:  equs5or  1708  sbal1yz  1874  copsexg  3972
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