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Theorem axc11n11r 32986
Description: Proof of axc11n 2474 from { ax-1 6-- ax-7 2104, axc9 2470, axc11r 2361 } (note that axc16 2312 is provable from { ax-1 6-- ax-7 2104, axc11r 2361 }).

Note that axc11n 2474 proves (over minimal calculus) that axc11 2478 and axc11r 2361 are equivalent. Therefore, axc11n11 32985 and axc11n11r 32986 prove that one can use one or the other as an axiom, provided one assumes the axioms listed above (axc11 2478 appears slightly stronger since axc11n11r 32986 requires axc9 2470 while axc11n11 32985 does not).

(Contributed by BJ, 6-Jul-2021.) (Proof modification is discouraged.)

Assertion
Ref Expression
axc11n11r (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥)

Proof of Theorem axc11n11r
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 equcomi 2113 . . . . 5 (𝑥 = 𝑦𝑦 = 𝑥)
2 axc16 2312 . . . . 5 (∀𝑦 𝑦 = 𝑧 → (𝑦 = 𝑥 → ∀𝑦 𝑦 = 𝑥))
31, 2syl5 34 . . . 4 (∀𝑦 𝑦 = 𝑧 → (𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥))
43spsd 2222 . . 3 (∀𝑦 𝑦 = 𝑧 → (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥))
54exlimiv 2021 . 2 (∃𝑧𝑦 𝑦 = 𝑧 → (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥))
6 alnex 1861 . . 3 (∀𝑧 ¬ ∀𝑦 𝑦 = 𝑧 ↔ ¬ ∃𝑧𝑦 𝑦 = 𝑧)
7 ax6evr 2111 . . . . 5 𝑧 𝑥 = 𝑧
8 19.29 1963 . . . . 5 ((∀𝑧 ¬ ∀𝑦 𝑦 = 𝑧 ∧ ∃𝑧 𝑥 = 𝑧) → ∃𝑧(¬ ∀𝑦 𝑦 = 𝑧𝑥 = 𝑧))
97, 8mpan2 674 . . . 4 (∀𝑧 ¬ ∀𝑦 𝑦 = 𝑧 → ∃𝑧(¬ ∀𝑦 𝑦 = 𝑧𝑥 = 𝑧))
10 axc9 2470 . . . . . . . . . . . 12 (¬ ∀𝑦 𝑦 = 𝑥 → (¬ ∀𝑦 𝑦 = 𝑧 → (𝑥 = 𝑧 → ∀𝑦 𝑥 = 𝑧)))
1110impcom 396 . . . . . . . . . . 11 ((¬ ∀𝑦 𝑦 = 𝑧 ∧ ¬ ∀𝑦 𝑦 = 𝑥) → (𝑥 = 𝑧 → ∀𝑦 𝑥 = 𝑧))
12 axc11r 2361 . . . . . . . . . . 11 (∀𝑥 𝑥 = 𝑦 → (∀𝑦 𝑥 = 𝑧 → ∀𝑥 𝑥 = 𝑧))
1311, 12syl9 77 . . . . . . . . . 10 ((¬ ∀𝑦 𝑦 = 𝑧 ∧ ¬ ∀𝑦 𝑦 = 𝑥) → (∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑧 → ∀𝑥 𝑥 = 𝑧)))
14 aev 2151 . . . . . . . . . 10 (∀𝑥 𝑥 = 𝑧 → ∀𝑦 𝑦 = 𝑥)
1513, 14syl8 76 . . . . . . . . 9 ((¬ ∀𝑦 𝑦 = 𝑧 ∧ ¬ ∀𝑦 𝑦 = 𝑥) → (∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑧 → ∀𝑦 𝑦 = 𝑥)))
1615ex 399 . . . . . . . 8 (¬ ∀𝑦 𝑦 = 𝑧 → (¬ ∀𝑦 𝑦 = 𝑥 → (∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑧 → ∀𝑦 𝑦 = 𝑥))))
1716com24 95 . . . . . . 7 (¬ ∀𝑦 𝑦 = 𝑧 → (𝑥 = 𝑧 → (∀𝑥 𝑥 = 𝑦 → (¬ ∀𝑦 𝑦 = 𝑥 → ∀𝑦 𝑦 = 𝑥))))
1817imp 395 . . . . . 6 ((¬ ∀𝑦 𝑦 = 𝑧𝑥 = 𝑧) → (∀𝑥 𝑥 = 𝑦 → (¬ ∀𝑦 𝑦 = 𝑥 → ∀𝑦 𝑦 = 𝑥)))
19 pm2.18 125 . . . . . 6 ((¬ ∀𝑦 𝑦 = 𝑥 → ∀𝑦 𝑦 = 𝑥) → ∀𝑦 𝑦 = 𝑥)
2018, 19syl6 35 . . . . 5 ((¬ ∀𝑦 𝑦 = 𝑧𝑥 = 𝑧) → (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥))
2120exlimiv 2021 . . . 4 (∃𝑧(¬ ∀𝑦 𝑦 = 𝑧𝑥 = 𝑧) → (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥))
229, 21syl 17 . . 3 (∀𝑧 ¬ ∀𝑦 𝑦 = 𝑧 → (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥))
236, 22sylbir 226 . 2 (¬ ∃𝑧𝑦 𝑦 = 𝑧 → (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥))
245, 23pm2.61i 176 1 (∀𝑥 𝑥 = 𝑦 → ∀𝑦 𝑦 = 𝑥)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 384  wal 1635  wex 1859
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1877  ax-4 1894  ax-5 2001  ax-6 2068  ax-7 2104  ax-10 2185  ax-12 2214  ax-13 2420
This theorem depends on definitions:  df-bi 198  df-an 385  df-or 866  df-tru 1641  df-ex 1860  df-nf 1864
This theorem is referenced by: (None)
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