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Theorem dvelimor 1894
 Description: Disjunctive distinct variable constraint elimination. A user of this theorem starts with a formula 𝜑 (containing 𝑧) and a distinct variable constraint between 𝑥 and 𝑧. The theorem makes it possible to replace the distinct variable constraint with the disjunct ∀𝑥𝑥 = 𝑦 (𝜓 is just a version of 𝜑 with 𝑦 substituted for 𝑧). (Contributed by Jim Kingdon, 11-May-2018.)
Hypotheses
Ref Expression
dvelimor.1 𝑥𝜑
dvelimor.2 (𝑧 = 𝑦 → (𝜑𝜓))
Assertion
Ref Expression
dvelimor (∀𝑥 𝑥 = 𝑦 ∨ Ⅎ𝑥𝜓)
Distinct variable groups:   𝜓,𝑧   𝑥,𝑧
Allowed substitution hints:   𝜑(𝑥,𝑦,𝑧)   𝜓(𝑥,𝑦)

Proof of Theorem dvelimor
StepHypRef Expression
1 ax-bndl 1399 . . . . . 6 (∀𝑥 𝑥 = 𝑧 ∨ (∀𝑥 𝑥 = 𝑦 ∨ ∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)))
2 orcom 647 . . . . . . 7 ((∀𝑥 𝑥 = 𝑦 ∨ ∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)) ↔ (∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦) ∨ ∀𝑥 𝑥 = 𝑦))
32orbi2i 679 . . . . . 6 ((∀𝑥 𝑥 = 𝑧 ∨ (∀𝑥 𝑥 = 𝑦 ∨ ∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦))) ↔ (∀𝑥 𝑥 = 𝑧 ∨ (∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦) ∨ ∀𝑥 𝑥 = 𝑦)))
41, 3mpbi 133 . . . . 5 (∀𝑥 𝑥 = 𝑧 ∨ (∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦) ∨ ∀𝑥 𝑥 = 𝑦))
5 orass 684 . . . . 5 (((∀𝑥 𝑥 = 𝑧 ∨ ∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)) ∨ ∀𝑥 𝑥 = 𝑦) ↔ (∀𝑥 𝑥 = 𝑧 ∨ (∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦) ∨ ∀𝑥 𝑥 = 𝑦)))
64, 5mpbir 134 . . . 4 ((∀𝑥 𝑥 = 𝑧 ∨ ∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)) ∨ ∀𝑥 𝑥 = 𝑦)
7 nfae 1607 . . . . . . 7 𝑧𝑥 𝑥 = 𝑧
8 a16nf 1746 . . . . . . 7 (∀𝑥 𝑥 = 𝑧 → Ⅎ𝑥(𝑧 = 𝑦𝜑))
97, 8alrimi 1415 . . . . . 6 (∀𝑥 𝑥 = 𝑧 → ∀𝑧𝑥(𝑧 = 𝑦𝜑))
10 df-nf 1350 . . . . . . . 8 (Ⅎ𝑥 𝑧 = 𝑦 ↔ ∀𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦))
11 id 19 . . . . . . . . 9 (Ⅎ𝑥 𝑧 = 𝑦 → Ⅎ𝑥 𝑧 = 𝑦)
12 dvelimor.1 . . . . . . . . . 10 𝑥𝜑
1312a1i 9 . . . . . . . . 9 (Ⅎ𝑥 𝑧 = 𝑦 → Ⅎ𝑥𝜑)
1411, 13nfimd 1477 . . . . . . . 8 (Ⅎ𝑥 𝑧 = 𝑦 → Ⅎ𝑥(𝑧 = 𝑦𝜑))
1510, 14sylbir 125 . . . . . . 7 (∀𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦) → Ⅎ𝑥(𝑧 = 𝑦𝜑))
1615alimi 1344 . . . . . 6 (∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦) → ∀𝑧𝑥(𝑧 = 𝑦𝜑))
179, 16jaoi 636 . . . . 5 ((∀𝑥 𝑥 = 𝑧 ∨ ∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)) → ∀𝑧𝑥(𝑧 = 𝑦𝜑))
1817orim1i 677 . . . 4 (((∀𝑥 𝑥 = 𝑧 ∨ ∀𝑧𝑥(𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)) ∨ ∀𝑥 𝑥 = 𝑦) → (∀𝑧𝑥(𝑧 = 𝑦𝜑) ∨ ∀𝑥 𝑥 = 𝑦))
196, 18ax-mp 7 . . 3 (∀𝑧𝑥(𝑧 = 𝑦𝜑) ∨ ∀𝑥 𝑥 = 𝑦)
20 orcom 647 . . 3 ((∀𝑧𝑥(𝑧 = 𝑦𝜑) ∨ ∀𝑥 𝑥 = 𝑦) ↔ (∀𝑥 𝑥 = 𝑦 ∨ ∀𝑧𝑥(𝑧 = 𝑦𝜑)))
2119, 20mpbi 133 . 2 (∀𝑥 𝑥 = 𝑦 ∨ ∀𝑧𝑥(𝑧 = 𝑦𝜑))
22 nfalt 1470 . . . 4 (∀𝑧𝑥(𝑧 = 𝑦𝜑) → Ⅎ𝑥𝑧(𝑧 = 𝑦𝜑))
23 ax-17 1419 . . . . . 6 (𝜓 → ∀𝑧𝜓)
24 dvelimor.2 . . . . . 6 (𝑧 = 𝑦 → (𝜑𝜓))
2523, 24equsalh 1614 . . . . 5 (∀𝑧(𝑧 = 𝑦𝜑) ↔ 𝜓)
2625nfbii 1362 . . . 4 (Ⅎ𝑥𝑧(𝑧 = 𝑦𝜑) ↔ Ⅎ𝑥𝜓)
2722, 26sylib 127 . . 3 (∀𝑧𝑥(𝑧 = 𝑦𝜑) → Ⅎ𝑥𝜓)
2827orim2i 678 . 2 ((∀𝑥 𝑥 = 𝑦 ∨ ∀𝑧𝑥(𝑧 = 𝑦𝜑)) → (∀𝑥 𝑥 = 𝑦 ∨ Ⅎ𝑥𝜓))
2921, 28ax-mp 7 1 (∀𝑥 𝑥 = 𝑦 ∨ Ⅎ𝑥𝜓)
 Colors of variables: wff set class Syntax hints:   → wi 4   ↔ wb 98   ∨ wo 629  ∀wal 1241  Ⅎwnf 1349 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 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428 This theorem depends on definitions:  df-bi 110  df-nf 1350  df-sb 1646 This theorem is referenced by:  nfsb4or  1899  rgen2a  2375
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