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Theorem sgrpass 17113
 Description: A semigroup operation is associative. (Contributed by FL, 2-Nov-2009.) (Revised by AV, 30-Jan-2020.)
Hypotheses
Ref Expression
sgrpass.b 𝐵 = (Base‘𝐺)
sgrpass.o = (+g𝐺)
Assertion
Ref Expression
sgrpass ((𝐺 ∈ SGrp ∧ (𝑋𝐵𝑌𝐵𝑍𝐵)) → ((𝑋 𝑌) 𝑍) = (𝑋 (𝑌 𝑍)))

Proof of Theorem sgrpass
Dummy variables 𝑥 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 sgrpass.b . . . 4 𝐵 = (Base‘𝐺)
2 sgrpass.o . . . 4 = (+g𝐺)
31, 2issgrp 17108 . . 3 (𝐺 ∈ SGrp ↔ (𝐺 ∈ Mgm ∧ ∀𝑥𝐵𝑦𝐵𝑧𝐵 ((𝑥 𝑦) 𝑧) = (𝑥 (𝑦 𝑧))))
4 oveq1 6556 . . . . . . . 8 (𝑥 = 𝑋 → (𝑥 𝑦) = (𝑋 𝑦))
54oveq1d 6564 . . . . . . 7 (𝑥 = 𝑋 → ((𝑥 𝑦) 𝑧) = ((𝑋 𝑦) 𝑧))
6 oveq1 6556 . . . . . . 7 (𝑥 = 𝑋 → (𝑥 (𝑦 𝑧)) = (𝑋 (𝑦 𝑧)))
75, 6eqeq12d 2625 . . . . . 6 (𝑥 = 𝑋 → (((𝑥 𝑦) 𝑧) = (𝑥 (𝑦 𝑧)) ↔ ((𝑋 𝑦) 𝑧) = (𝑋 (𝑦 𝑧))))
8 oveq2 6557 . . . . . . . 8 (𝑦 = 𝑌 → (𝑋 𝑦) = (𝑋 𝑌))
98oveq1d 6564 . . . . . . 7 (𝑦 = 𝑌 → ((𝑋 𝑦) 𝑧) = ((𝑋 𝑌) 𝑧))
10 oveq1 6556 . . . . . . . 8 (𝑦 = 𝑌 → (𝑦 𝑧) = (𝑌 𝑧))
1110oveq2d 6565 . . . . . . 7 (𝑦 = 𝑌 → (𝑋 (𝑦 𝑧)) = (𝑋 (𝑌 𝑧)))
129, 11eqeq12d 2625 . . . . . 6 (𝑦 = 𝑌 → (((𝑋 𝑦) 𝑧) = (𝑋 (𝑦 𝑧)) ↔ ((𝑋 𝑌) 𝑧) = (𝑋 (𝑌 𝑧))))
13 oveq2 6557 . . . . . . 7 (𝑧 = 𝑍 → ((𝑋 𝑌) 𝑧) = ((𝑋 𝑌) 𝑍))
14 oveq2 6557 . . . . . . . 8 (𝑧 = 𝑍 → (𝑌 𝑧) = (𝑌 𝑍))
1514oveq2d 6565 . . . . . . 7 (𝑧 = 𝑍 → (𝑋 (𝑌 𝑧)) = (𝑋 (𝑌 𝑍)))
1613, 15eqeq12d 2625 . . . . . 6 (𝑧 = 𝑍 → (((𝑋 𝑌) 𝑧) = (𝑋 (𝑌 𝑧)) ↔ ((𝑋 𝑌) 𝑍) = (𝑋 (𝑌 𝑍))))
177, 12, 16rspc3v 3296 . . . . 5 ((𝑋𝐵𝑌𝐵𝑍𝐵) → (∀𝑥𝐵𝑦𝐵𝑧𝐵 ((𝑥 𝑦) 𝑧) = (𝑥 (𝑦 𝑧)) → ((𝑋 𝑌) 𝑍) = (𝑋 (𝑌 𝑍))))
1817com12 32 . . . 4 (∀𝑥𝐵𝑦𝐵𝑧𝐵 ((𝑥 𝑦) 𝑧) = (𝑥 (𝑦 𝑧)) → ((𝑋𝐵𝑌𝐵𝑍𝐵) → ((𝑋 𝑌) 𝑍) = (𝑋 (𝑌 𝑍))))
1918adantl 481 . . 3 ((𝐺 ∈ Mgm ∧ ∀𝑥𝐵𝑦𝐵𝑧𝐵 ((𝑥 𝑦) 𝑧) = (𝑥 (𝑦 𝑧))) → ((𝑋𝐵𝑌𝐵𝑍𝐵) → ((𝑋 𝑌) 𝑍) = (𝑋 (𝑌 𝑍))))
203, 19sylbi 206 . 2 (𝐺 ∈ SGrp → ((𝑋𝐵𝑌𝐵𝑍𝐵) → ((𝑋 𝑌) 𝑍) = (𝑋 (𝑌 𝑍))))
2120imp 444 1 ((𝐺 ∈ SGrp ∧ (𝑋𝐵𝑌𝐵𝑍𝐵)) → ((𝑋 𝑌) 𝑍) = (𝑋 (𝑌 𝑍)))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 383   ∧ w3a 1031   = wceq 1475   ∈ wcel 1977  ∀wral 2896  ‘cfv 5804  (class class class)co 6549  Basecbs 15695  +gcplusg 15768  Mgmcmgm 17063  SGrpcsgrp 17106 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  ax-nul 4717 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ral 2901  df-rex 2902  df-rab 2905  df-v 3175  df-sbc 3403  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-if 4037  df-sn 4126  df-pr 4128  df-op 4132  df-uni 4373  df-br 4584  df-iota 5768  df-fv 5812  df-ov 6552  df-sgrp 17107 This theorem is referenced by:  mndass  17125  dfgrp2  17270  dfgrp3lem  17336  dfgrp3e  17338  mulgnndir  17392
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