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Theorem pm13.183 3549
 Description: Compare theorem *13.183 in [WhiteheadRussell] p. 178. Only 𝐴 is required to be a set. (Contributed by Andrew Salmon, 3-Jun-2011.) Avoid ax-13 2334. (Revised by Wolf Lammen, 29-Apr-2023.)
Assertion
Ref Expression
pm13.183 (𝐴𝑉 → (𝐴 = 𝐵 ↔ ∀𝑧(𝑧 = 𝐴𝑧 = 𝐵)))
Distinct variable groups:   𝑧,𝐴   𝑧,𝐵
Allowed substitution hint:   𝑉(𝑧)

Proof of Theorem pm13.183
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 eqeq1 2782 . 2 (𝑦 = 𝐴 → (𝑦 = 𝐵𝐴 = 𝐵))
2 eqeq2 2789 . . . 4 (𝑦 = 𝐴 → (𝑧 = 𝑦𝑧 = 𝐴))
32bibi1d 335 . . 3 (𝑦 = 𝐴 → ((𝑧 = 𝑦𝑧 = 𝐵) ↔ (𝑧 = 𝐴𝑧 = 𝐵)))
43albidv 1963 . 2 (𝑦 = 𝐴 → (∀𝑧(𝑧 = 𝑦𝑧 = 𝐵) ↔ ∀𝑧(𝑧 = 𝐴𝑧 = 𝐵)))
5 eqeq2 2789 . . . 4 (𝑦 = 𝐵 → (𝑧 = 𝑦𝑧 = 𝐵))
65alrimiv 1970 . . 3 (𝑦 = 𝐵 → ∀𝑧(𝑧 = 𝑦𝑧 = 𝐵))
7 stdpc4v 2244 . . . 4 (∀𝑧(𝑧 = 𝑦𝑧 = 𝐵) → [𝑦 / 𝑧](𝑧 = 𝑦𝑧 = 𝐵))
8 sbbiv 2282 . . . . 5 ([𝑦 / 𝑧](𝑧 = 𝑦𝑧 = 𝐵) ↔ ([𝑦 / 𝑧]𝑧 = 𝑦 ↔ [𝑦 / 𝑧]𝑧 = 𝐵))
9 eqsb3v 2885 . . . . . . 7 ([𝑦 / 𝑧]𝑧 = 𝐵𝑦 = 𝐵)
109bibi2i 329 . . . . . 6 (([𝑦 / 𝑧]𝑧 = 𝑦 ↔ [𝑦 / 𝑧]𝑧 = 𝐵) ↔ ([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵))
11 equsb1v 2049 . . . . . . 7 [𝑦 / 𝑧]𝑧 = 𝑦
12 biimp 207 . . . . . . 7 (([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵) → ([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵))
1311, 12mpi 20 . . . . . 6 (([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵) → 𝑦 = 𝐵)
1410, 13sylbi 209 . . . . 5 (([𝑦 / 𝑧]𝑧 = 𝑦 ↔ [𝑦 / 𝑧]𝑧 = 𝐵) → 𝑦 = 𝐵)
158, 14sylbi 209 . . . 4 ([𝑦 / 𝑧](𝑧 = 𝑦𝑧 = 𝐵) → 𝑦 = 𝐵)
167, 15syl 17 . . 3 (∀𝑧(𝑧 = 𝑦𝑧 = 𝐵) → 𝑦 = 𝐵)
176, 16impbii 201 . 2 (𝑦 = 𝐵 ↔ ∀𝑧(𝑧 = 𝑦𝑧 = 𝐵))
181, 4, 17vtoclbg 3468 1 (𝐴𝑉 → (𝐴 = 𝐵 ↔ ∀𝑧(𝑧 = 𝐴𝑧 = 𝐵)))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 198  ∀wal 1599   = wceq 1601  [wsb 2011   ∈ wcel 2107 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1839  ax-4 1853  ax-5 1953  ax-6 2021  ax-7 2055  ax-9 2116  ax-10 2135  ax-12 2163  ax-ext 2754 This theorem depends on definitions:  df-bi 199  df-an 387  df-or 837  df-tru 1605  df-ex 1824  df-nf 1828  df-sb 2012  df-clab 2764  df-cleq 2770  df-clel 2774  df-v 3400 This theorem is referenced by:  mpt22eqb  7046
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