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Theorem sucidALTVD 38128
Description: A set belongs to its successor. Alternate proof of sucid 5721. The following User's Proof is a Virtual Deduction proof completed automatically by the tools program completeusersproof.cmd, which invokes Mel L. O'Cat's mmj2 and Norm Megill's Metamath Proof Assistant. sucidALT 38129 is sucidALTVD 38128 without virtual deductions and was automatically derived from sucidALTVD 38128. This proof illustrates that completeusersproof.cmd will generate a Metamath proof from any User's Proof which is "conventional" in the sense that no step is a virtual deduction, provided that all necessary unification theorems and transformation deductions are in completeusersproof.cmd automatically converts such a conventional proof into a Virtual Deduction proof for which each step happens to be a 0-virtual hypothesis virtual deduction. The user does not need to search for reference theorem labels or deduction labels nor does he(she) need to use theorems and deductions which unify with reference theorems and deductions in All that is necessary is that each theorem or deduction of the User's Proof unifies with some reference theorem or deduction in or is a semantic variation of some theorem or deduction which unifies with some reference theorem or deduction in The definition of "semantic variation" has not been precisely defined. If it is obvious that a theorem or deduction has the same meaning as another theorem or deduction, then it is a semantic variation of the latter theorem or deduction. For example, step 4 of the User's Proof is a semantic variation of the definition (axiom) suc 𝐴 = (𝐴 ∪ {𝐴}), which unifies with df-suc 5646, a reference definition (axiom) in Also, a theorem or deduction is said to be a semantic variation of another theorem or deduction if it is obvious upon cursory inspection that it has the same meaning as a weaker form of the latter theorem or deduction. For example, the deduction Ord 𝐴 infers 𝑥𝐴𝑦𝐴(𝑥𝑦𝑥 = 𝑦𝑦𝑥) is a semantic variation of the theorem (Ord 𝐴 ↔ (Tr 𝐴 ∧ ∀𝑥𝐴 𝑦𝐴(𝑥𝑦𝑥 = 𝑦𝑦𝑥))), which unifies with the reference definition (axiom) dford2 8400.
h1:: 𝐴 ∈ V
2:1: 𝐴 ∈ {𝐴}
3:2: 𝐴 ∈ ({𝐴} ∪ 𝐴)
4:: suc 𝐴 = ({𝐴} ∪ 𝐴)
qed:3,4: 𝐴 ∈ suc 𝐴
(Contributed by Alan Sare, 18-Feb-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
Ref Expression
sucidALTVD.1 𝐴 ∈ V
Ref Expression
sucidALTVD 𝐴 ∈ suc 𝐴

Proof of Theorem sucidALTVD
StepHypRef Expression
1 sucidALTVD.1 . . . 4 𝐴 ∈ V
21snid 4155 . . 3 𝐴 ∈ {𝐴}
3 elun1 3742 . . 3 (𝐴 ∈ {𝐴} → 𝐴 ∈ ({𝐴} ∪ 𝐴))
42, 3e0a 38020 . 2 𝐴 ∈ ({𝐴} ∪ 𝐴)
5 df-suc 5646 . . 3 suc 𝐴 = (𝐴 ∪ {𝐴})
65equncomi 3721 . 2 suc 𝐴 = ({𝐴} ∪ 𝐴)
74, 6eleqtrri 2687 1 𝐴 ∈ suc 𝐴
Colors of variables: wff setvar class
Syntax hints:  wcel 1977  Vcvv 3173  cun 3538  {csn 4125  suc csuc 5642
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590
This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-v 3175  df-un 3545  df-in 3547  df-ss 3554  df-sn 4126  df-suc 5646
This theorem is referenced by: (None)
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