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Theorem unisnALT 37967
 Description: A set equals the union of its singleton. Theorem 8.2 of [Quine] p. 53. The User manually input on a mmj2 Proof Worksheet, without labels, all steps of unisnALT 37967 except 1, 11, 15, 21, and 30. With execution of the mmj2 unification command, mmj2 could find labels for all steps except for 2, 12, 16, 22, and 31 (and the then non-existing steps 1, 11, 15, 21, and 30) . mmj2 could not find reference theorems for those five steps because the hypothesis field of each of these steps was empty and none of those steps unifies with a theorem in set.mm. Each of these five steps is a semantic variation of a theorem in set.mm and is 2-step provable. mmj2 does not have the ability to automatically generate the semantic variation in set.mm of a theorem in a mmj2 Proof Worksheet unless the theorem in the Proof Worksheet is labeled with a 1-hypothesis deduction whose hypothesis is a theorem in set.mm which unifies with the theorem in the Proof Worksheet. The stepprover.c program, which invokes mmj2, has this capability. stepprover.c automatically generated steps 1, 11, 15, 21, and 30, labeled all steps, and generated the RPN proof of unisnALT 37967. Roughly speaking, stepprover.c added to the Proof Worksheet a labeled duplicate step of each non-unifying theorem for each label in a text file, labels.txt, containing a list of labels provided by the User. Upon mmj2 unification, stepprover.c identified a label for each of the five theorems which 2-step proves it. For unisnALT 37967, the label list is a list of all 1-hypothesis propositional calculus deductions in set.mm. stepproverp.c is the same as stepprover.c except that it intermittently pauses during execution, allowing the User to observe the changes to a text file caused by the execution of particular statements of the program. (Contributed by Alan Sare, 19-Aug-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
Hypothesis
Ref Expression
unisnALT.1 𝐴 ∈ V
Assertion
Ref Expression
unisnALT {𝐴} = 𝐴

Proof of Theorem unisnALT
Dummy variables 𝑥 𝑞 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 eluni 4369 . . . . . 6 (𝑥 {𝐴} ↔ ∃𝑞(𝑥𝑞𝑞 ∈ {𝐴}))
21biimpi 204 . . . . 5 (𝑥 {𝐴} → ∃𝑞(𝑥𝑞𝑞 ∈ {𝐴}))
3 id 22 . . . . . . . . 9 ((𝑥𝑞𝑞 ∈ {𝐴}) → (𝑥𝑞𝑞 ∈ {𝐴}))
4 simpl 471 . . . . . . . . 9 ((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝑞)
53, 4syl 17 . . . . . . . 8 ((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝑞)
6 simpr 475 . . . . . . . . . 10 ((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑞 ∈ {𝐴})
73, 6syl 17 . . . . . . . . 9 ((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑞 ∈ {𝐴})
8 elsni 4141 . . . . . . . . 9 (𝑞 ∈ {𝐴} → 𝑞 = 𝐴)
97, 8syl 17 . . . . . . . 8 ((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑞 = 𝐴)
10 eleq2 2676 . . . . . . . . 9 (𝑞 = 𝐴 → (𝑥𝑞𝑥𝐴))
1110biimpac 501 . . . . . . . 8 ((𝑥𝑞𝑞 = 𝐴) → 𝑥𝐴)
125, 9, 11syl2anc 690 . . . . . . 7 ((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴)
1312ax-gen 1712 . . . . . 6 𝑞((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴)
14 19.23v 1888 . . . . . . 7 (∀𝑞((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴) ↔ (∃𝑞(𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴))
1514biimpi 204 . . . . . 6 (∀𝑞((𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴) → (∃𝑞(𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴))
1613, 15ax-mp 5 . . . . 5 (∃𝑞(𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴)
17 pm3.35 608 . . . . 5 ((∃𝑞(𝑥𝑞𝑞 ∈ {𝐴}) ∧ (∃𝑞(𝑥𝑞𝑞 ∈ {𝐴}) → 𝑥𝐴)) → 𝑥𝐴)
182, 16, 17sylancl 692 . . . 4 (𝑥 {𝐴} → 𝑥𝐴)
1918ax-gen 1712 . . 3 𝑥(𝑥 {𝐴} → 𝑥𝐴)
20 dfss2 3556 . . . 4 ( {𝐴} ⊆ 𝐴 ↔ ∀𝑥(𝑥 {𝐴} → 𝑥𝐴))
2120biimpri 216 . . 3 (∀𝑥(𝑥 {𝐴} → 𝑥𝐴) → {𝐴} ⊆ 𝐴)
2219, 21ax-mp 5 . 2 {𝐴} ⊆ 𝐴
23 id 22 . . . . 5 (𝑥𝐴𝑥𝐴)
24 unisnALT.1 . . . . . 6 𝐴 ∈ V
2524snid 4154 . . . . 5 𝐴 ∈ {𝐴}
26 elunii 4371 . . . . 5 ((𝑥𝐴𝐴 ∈ {𝐴}) → 𝑥 {𝐴})
2723, 25, 26sylancl 692 . . . 4 (𝑥𝐴𝑥 {𝐴})
2827ax-gen 1712 . . 3 𝑥(𝑥𝐴𝑥 {𝐴})
29 dfss2 3556 . . . 4 (𝐴 {𝐴} ↔ ∀𝑥(𝑥𝐴𝑥 {𝐴}))
3029biimpri 216 . . 3 (∀𝑥(𝑥𝐴𝑥 {𝐴}) → 𝐴 {𝐴})
3128, 30ax-mp 5 . 2 𝐴 {𝐴}
3222, 31eqssi 3583 1 {𝐴} = 𝐴
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 382  ∀wal 1472   = wceq 1474  ∃wex 1694   ∈ wcel 1976  Vcvv 3172   ⊆ wss 3539  {csn 4124  ∪ cuni 4366 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1712  ax-4 1727  ax-5 1826  ax-6 1874  ax-7 1921  ax-10 2005  ax-11 2020  ax-12 2033  ax-13 2233  ax-ext 2589 This theorem depends on definitions:  df-bi 195  df-or 383  df-an 384  df-tru 1477  df-ex 1695  df-nf 1700  df-sb 1867  df-clab 2596  df-cleq 2602  df-clel 2605  df-nfc 2739  df-v 3174  df-in 3546  df-ss 3553  df-sn 4125  df-uni 4367 This theorem is referenced by: (None)
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