grpideu - Intuitionistic Logic Explorer

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Theorem grpideu 13818

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	⊢ + = (+_g‘𝐺)
grpinvex.p	⊢ 0 = (0_g‘𝐺)

**Assertion**
Ref	Expression
grpideu	⊢ (𝐺 ∈ Grp → ∃!𝑢 ∈ 𝐵 ∀𝑥 ∈ 𝐵 ((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**
Step	Hyp	Ref	Expression
1		grpmnd 13814	. 2 ⊢ (𝐺 ∈ Grp → 𝐺 ∈ Mnd)
2		grpcl.b	. . 3 ⊢ 𝐵 = (Base‘𝐺)
3		grpcl.p	. . 3 ⊢ + = (+_g‘𝐺)
4	2, 3	mndideu 13741	. 2 ⊢ (𝐺 ∈ Mnd → ∃!𝑢 ∈ 𝐵 ∀𝑥 ∈ 𝐵 ((𝑢 + 𝑥) = 𝑥 ∧ (𝑥 + 𝑢) = 𝑥))
5	1, 4	syl 14	1 ⊢ (𝐺 ∈ Grp → ∃!𝑢 ∈ 𝐵 ∀𝑥 ∈ 𝐵 ((𝑢 + 𝑥) = 𝑥 ∧ (𝑥 + 𝑢) = 𝑥))

Colors of variables: wff set class

This proof depends on syntax axioms: → wi 4 ∧ wa 104 = wceq 1402 ∈ wcel 2209 ∀wral 2528 ∃!wreu 2530 ‘cfv 5377 (class class class)co 6085 Basecbs 13354 +_gcplusg 13433 0_gc0g 13612 Mndcmnd 13731 Grpcgrp 13807

This proof depends on axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-io 721 ax-5 1500 ax-7 1501 ax-gen 1502 ax-ie1 1546 ax-ie2 1547 ax-8 1557 ax-10 1558 ax-11 1559 ax-i12 1560 ax-bndl 1562 ax-4 1563 ax-17 1579 ax-i9 1583 ax-ial 1587 ax-i5r 1588 ax-14 2212 ax-ext 2220 ax-sep 4249 ax-pow 4311 ax-pr 4346 ax-un 4578 ax-cnex 8270 ax-resscn 8271 ax-1re 8273 ax-addrcl 8276

This proof depends on definitions: df-bi 117 df-3an 1011 df-tru 1405 df-nf 1514 df-sb 1816 df-eu 2089 df-mo 2090 df-clab 2225 df-cleq 2231 df-clel 2234 df-nfc 2381 df-ral 2533 df-rex 2534 df-reu 2535 df-rmo 2536 df-rab 2537 df-v 2823 df-sbc 3052 df-un 3224 df-in 3226 df-ss 3233 df-pw 3690 df-sn 3715 df-pr 3716 df-op 3718 df-uni 3936 df-int 3971 df-br 4131 df-opab 4193 df-mpt 4194 df-id 4438 df-xp 4780 df-rel 4781 df-cnv 4782 df-co 4783 df-dm 4784 df-rn 4785 df-res 4786 df-iota 5337 df-fun 5379 df-fn 5380 df-fv 5385 df-ov 6088 df-inn 9306 df-2 9364 df-ndx 13357 df-slot 13358 df-base 13360 df-plusg 13446 df-mgm 13678 df-sgrp 13719 df-mnd 13732 df-grp 13810

This theorem is used by: (None)

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