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Theorem pm13.183 2754
Description: Compare theorem *13.183 in [WhiteheadRussell] p. 178. Only 𝐴 is required to be a set. (Contributed by Andrew Salmon, 3-Jun-2011.)
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 2094 . 2 (𝑦 = 𝐴 → (𝑦 = 𝐵𝐴 = 𝐵))
2 eqeq2 2097 . . . 4 (𝑦 = 𝐴 → (𝑧 = 𝑦𝑧 = 𝐴))
32bibi1d 231 . . 3 (𝑦 = 𝐴 → ((𝑧 = 𝑦𝑧 = 𝐵) ↔ (𝑧 = 𝐴𝑧 = 𝐵)))
43albidv 1752 . 2 (𝑦 = 𝐴 → (∀𝑧(𝑧 = 𝑦𝑧 = 𝐵) ↔ ∀𝑧(𝑧 = 𝐴𝑧 = 𝐵)))
5 eqeq2 2097 . . . 4 (𝑦 = 𝐵 → (𝑧 = 𝑦𝑧 = 𝐵))
65alrimiv 1802 . . 3 (𝑦 = 𝐵 → ∀𝑧(𝑧 = 𝑦𝑧 = 𝐵))
7 stdpc4 1705 . . . 4 (∀𝑧(𝑧 = 𝑦𝑧 = 𝐵) → [𝑦 / 𝑧](𝑧 = 𝑦𝑧 = 𝐵))
8 sbbi 1881 . . . . 5 ([𝑦 / 𝑧](𝑧 = 𝑦𝑧 = 𝐵) ↔ ([𝑦 / 𝑧]𝑧 = 𝑦 ↔ [𝑦 / 𝑧]𝑧 = 𝐵))
9 eqsb3 2191 . . . . . . 7 ([𝑦 / 𝑧]𝑧 = 𝐵𝑦 = 𝐵)
109bibi2i 225 . . . . . 6 (([𝑦 / 𝑧]𝑧 = 𝑦 ↔ [𝑦 / 𝑧]𝑧 = 𝐵) ↔ ([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵))
11 equsb1 1715 . . . . . . 7 [𝑦 / 𝑧]𝑧 = 𝑦
12 bi1 116 . . . . . . 7 (([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵) → ([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵))
1311, 12mpi 15 . . . . . 6 (([𝑦 / 𝑧]𝑧 = 𝑦𝑦 = 𝐵) → 𝑦 = 𝐵)
1410, 13sylbi 119 . . . . 5 (([𝑦 / 𝑧]𝑧 = 𝑦 ↔ [𝑦 / 𝑧]𝑧 = 𝐵) → 𝑦 = 𝐵)
158, 14sylbi 119 . . . 4 ([𝑦 / 𝑧](𝑧 = 𝑦𝑧 = 𝐵) → 𝑦 = 𝐵)
167, 15syl 14 . . 3 (∀𝑧(𝑧 = 𝑦𝑧 = 𝐵) → 𝑦 = 𝐵)
176, 16impbii 124 . 2 (𝑦 = 𝐵 ↔ ∀𝑧(𝑧 = 𝑦𝑧 = 𝐵))
181, 4, 17vtoclbg 2680 1 (𝐴𝑉 → (𝐴 = 𝐵 ↔ ∀𝑧(𝑧 = 𝐴𝑧 = 𝐵)))
Colors of variables: wff set class
Syntax hints:  wi 4  wb 103  wal 1287   = wceq 1289  wcel 1438  [wsb 1692
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070
This theorem depends on definitions:  df-bi 115  df-tru 1292  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-v 2621
This theorem is referenced by:  mpt22eqb  5754
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