MPE Home Metamath Proof Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >  grpideu Structured version   Visualization version   GIF version

Theorem grpideu 17197
Description: The two-sided identity element of a group is unique. Lemma 2.2.1(a) of [Herstein] p. 55. (Contributed by NM, 16-Aug-2011.) (Revised by Mario Carneiro, 8-Dec-2014.)
Hypotheses
Ref Expression
grpcl.b 𝐵 = (Base‘𝐺)
grpcl.p + = (+g𝐺)
grpinvex.p 0 = (0g𝐺)
Assertion
Ref Expression
grpideu (𝐺 ∈ Grp → ∃!𝑢𝐵𝑥𝐵 ((𝑢 + 𝑥) = 𝑥 ∧ (𝑥 + 𝑢) = 𝑥))
Distinct variable groups:   𝑥,𝑢,𝐵   𝑢,𝐺,𝑥   𝑢, + ,𝑥   𝑥, 0
Allowed substitution hint:   0 (𝑢)

Proof of Theorem grpideu
StepHypRef Expression
1 grpmnd 17193 . 2 (𝐺 ∈ Grp → 𝐺 ∈ Mnd)
2 grpcl.b . . 3 𝐵 = (Base‘𝐺)
3 grpcl.p . . 3 + = (+g𝐺)
42, 3mndideu 17068 . 2 (𝐺 ∈ Mnd → ∃!𝑢𝐵𝑥𝐵 ((𝑢 + 𝑥) = 𝑥 ∧ (𝑥 + 𝑢) = 𝑥))
51, 4syl 17 1 (𝐺 ∈ Grp → ∃!𝑢𝐵𝑥𝐵 ((𝑢 + 𝑥) = 𝑥 ∧ (𝑥 + 𝑢) = 𝑥))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 382   = wceq 1474  wcel 1975  wral 2890  ∃!wreu 2892  cfv 5785  (class class class)co 6522  Basecbs 15636  +gcplusg 15709  0gc0g 15864  Mndcmnd 17058  Grpcgrp 17186
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1711  ax-4 1726  ax-5 1825  ax-6 1873  ax-7 1920  ax-8 1977  ax-9 1984  ax-10 2004  ax-11 2019  ax-12 2031  ax-13 2227  ax-ext 2584  ax-nul 4707  ax-pow 4759
This theorem depends on definitions:  df-bi 195  df-or 383  df-an 384  df-3an 1032  df-tru 1477  df-ex 1695  df-nf 1700  df-sb 1866  df-eu 2456  df-mo 2457  df-clab 2591  df-cleq 2597  df-clel 2600  df-nfc 2734  df-ne 2776  df-ral 2895  df-rex 2896  df-reu 2897  df-rmo 2898  df-rab 2899  df-v 3169  df-sbc 3397  df-dif 3537  df-un 3539  df-in 3541  df-ss 3548  df-nul 3869  df-if 4031  df-sn 4120  df-pr 4122  df-op 4126  df-uni 4362  df-br 4573  df-iota 5749  df-fv 5793  df-ov 6525  df-mgm 17006  df-sgrp 17048  df-mnd 17059  df-grp 17189
This theorem is referenced by: (None)
  Copyright terms: Public domain W3C validator