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Theorem sgrp2nmndlem1 18090
Description: Lemma 1 for sgrp2nmnd 18097: 𝑀 is a magma, even if 𝐴 = 𝐵 (𝑀 is the trivial magma in this case, see mgmb1mgm1 17867). (Contributed by AV, 29-Jan-2020.)
Hypotheses
Ref Expression
mgm2nsgrp.s 𝑆 = {𝐴, 𝐵}
mgm2nsgrp.b (Base‘𝑀) = 𝑆
sgrp2nmnd.o (+g𝑀) = (𝑥𝑆, 𝑦𝑆 ↦ if(𝑥 = 𝐴, 𝐴, 𝐵))
Assertion
Ref Expression
sgrp2nmndlem1 ((𝐴𝑉𝐵𝑊) → 𝑀 ∈ Mgm)
Distinct variable groups:   𝑥,𝑆,𝑦   𝑥,𝐴,𝑦   𝑥,𝐵,𝑦   𝑥,𝑀
Allowed substitution hints:   𝑀(𝑦)   𝑉(𝑥,𝑦)   𝑊(𝑥,𝑦)

Proof of Theorem sgrp2nmndlem1
StepHypRef Expression
1 prid1g 4681 . . 3 (𝐴𝑉𝐴 ∈ {𝐴, 𝐵})
2 mgm2nsgrp.s . . 3 𝑆 = {𝐴, 𝐵}
31, 2eleqtrrdi 2927 . 2 (𝐴𝑉𝐴𝑆)
4 prid2g 4682 . . 3 (𝐵𝑊𝐵 ∈ {𝐴, 𝐵})
54, 2eleqtrrdi 2927 . 2 (𝐵𝑊𝐵𝑆)
6 mgm2nsgrp.b . . . 4 (Base‘𝑀) = 𝑆
76eqcomi 2833 . . 3 𝑆 = (Base‘𝑀)
8 sgrp2nmnd.o . . 3 (+g𝑀) = (𝑥𝑆, 𝑦𝑆 ↦ if(𝑥 = 𝐴, 𝐴, 𝐵))
9 ne0i 4283 . . . 4 (𝐴𝑆𝑆 ≠ ∅)
109adantr 484 . . 3 ((𝐴𝑆𝐵𝑆) → 𝑆 ≠ ∅)
11 simpll 766 . . 3 (((𝐴𝑆𝐵𝑆) ∧ (𝑥𝑆𝑦𝑆)) → 𝐴𝑆)
12 simplr 768 . . 3 (((𝐴𝑆𝐵𝑆) ∧ (𝑥𝑆𝑦𝑆)) → 𝐵𝑆)
137, 8, 10, 11, 12opifismgm 17871 . 2 ((𝐴𝑆𝐵𝑆) → 𝑀 ∈ Mgm)
143, 5, 13syl2an 598 1 ((𝐴𝑉𝐵𝑊) → 𝑀 ∈ Mgm)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 399   = wceq 1538  wcel 2115  wne 3014  c0 4276  ifcif 4450  {cpr 4552  cfv 6345  cmpo 7153  Basecbs 16485  +gcplusg 16567  Mgmcmgm 17852
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1971  ax-7 2016  ax-8 2117  ax-9 2125  ax-10 2146  ax-11 2162  ax-12 2179  ax-ext 2796  ax-sep 5190  ax-nul 5197  ax-pow 5254  ax-pr 5318  ax-un 7457
This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2071  df-mo 2624  df-eu 2655  df-clab 2803  df-cleq 2817  df-clel 2896  df-nfc 2964  df-ne 3015  df-ral 3138  df-rex 3139  df-rab 3142  df-v 3482  df-sbc 3759  df-csb 3867  df-dif 3922  df-un 3924  df-in 3926  df-ss 3936  df-nul 4277  df-if 4451  df-sn 4551  df-pr 4553  df-op 4557  df-uni 4825  df-iun 4907  df-br 5054  df-opab 5116  df-mpt 5134  df-id 5448  df-xp 5549  df-rel 5550  df-cnv 5551  df-co 5552  df-dm 5553  df-rn 5554  df-res 5555  df-ima 5556  df-iota 6304  df-fun 6347  df-fn 6348  df-f 6349  df-fv 6353  df-ov 7154  df-oprab 7155  df-mpo 7156  df-1st 7686  df-2nd 7687  df-mgm 17854
This theorem is referenced by:  sgrp2nmndlem4  18095
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