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Theorem grpoideu 31093
Description: The left identity element of a group is unique. Lemma 2.2.1(a) of [Herstein] p. 55. (Contributed by NM, 14-Oct-2006.) (New usage is discouraged.)
Hypothesis
Ref Expression
grpfo.1 𝑋 = ran 𝐺
Assertion
Ref Expression
grpoideu (𝐺 ∈ GrpOp → ∃!𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥)
Distinct variable groups:   𝑥,𝑢,𝐺   𝑢,𝑋,𝑥

Proof of Theorem grpoideu
Dummy variables 𝑤 𝑦 𝑧 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 grpfo.1 . . . 4 𝑋 = ran 𝐺
21grpoidinv 31092 . . 3 (𝐺 ∈ GrpOp → ∃𝑢 ∈ 𝑋 ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)))
3 simpll 779 . . . . . . . . 9 ((((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → (𝑢𝐺𝑧) = 𝑧)
43ralimi 3100 . . . . . . . 8 (∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → ∀𝑧 ∈ 𝑋 (𝑢𝐺𝑧) = 𝑧)
5 oveq2 7420 . . . . . . . . . 10 (𝑧 = 𝑥 → (𝑢𝐺𝑧) = (𝑢𝐺𝑥))
6 id 23 . . . . . . . . . 10 (𝑧 = 𝑥 → 𝑧 = 𝑥)
75, 6eqeq12d 2777 . . . . . . . . 9 (𝑧 = 𝑥 → ((𝑢𝐺𝑧) = 𝑧 ↔ (𝑢𝐺𝑥) = 𝑥))
87cbvralvw 3241 . . . . . . . 8 (∀𝑧 ∈ 𝑋 (𝑢𝐺𝑧) = 𝑧 ↔ ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥)
94, 8sylib 221 . . . . . . 7 (∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥)
109adantl 487 . . . . . 6 (((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) → ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥)
119ad2antlr 740 . . . . . . . 8 ((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) → ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥)
12 simpr 490 . . . . . . . . . . . . . . . 16 ((((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))
1312ralimi 3100 . . . . . . . . . . . . . . 15 (∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → ∀𝑧 ∈ 𝑋 ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))
14 oveq2 7420 . . . . . . . . . . . . . . . . . . . 20 (𝑧 = 𝑤 → (𝑦𝐺𝑧) = (𝑦𝐺𝑤))
1514eqeq1d 2763 . . . . . . . . . . . . . . . . . . 19 (𝑧 = 𝑤 → ((𝑦𝐺𝑧) = 𝑢 ↔ (𝑦𝐺𝑤) = 𝑢))
16 oveq1 7419 . . . . . . . . . . . . . . . . . . . 20 (𝑧 = 𝑤 → (𝑧𝐺𝑦) = (𝑤𝐺𝑦))
1716eqeq1d 2763 . . . . . . . . . . . . . . . . . . 19 (𝑧 = 𝑤 → ((𝑧𝐺𝑦) = 𝑢 ↔ (𝑤𝐺𝑦) = 𝑢))
1815, 17anbi12d 644 . . . . . . . . . . . . . . . . . 18 (𝑧 = 𝑤 → (((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢) ↔ ((𝑦𝐺𝑤) = 𝑢 ∧ (𝑤𝐺𝑦) = 𝑢)))
1918rexbidv 3187 . . . . . . . . . . . . . . . . 17 (𝑧 = 𝑤 → (∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢) ↔ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑤) = 𝑢 ∧ (𝑤𝐺𝑦) = 𝑢)))
2019rspcva 3575 . . . . . . . . . . . . . . . 16 ((𝑤 ∈ 𝑋 ∧ ∀𝑧 ∈ 𝑋 ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑤) = 𝑢 ∧ (𝑤𝐺𝑦) = 𝑢))
2120adantll 727 . . . . . . . . . . . . . . 15 (((𝐺 ∈ GrpOp ∧ 𝑤 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑤) = 𝑢 ∧ (𝑤𝐺𝑦) = 𝑢))
2213, 21sylan2 605 . . . . . . . . . . . . . 14 (((𝐺 ∈ GrpOp ∧ 𝑤 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) → ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑤) = 𝑢 ∧ (𝑤𝐺𝑦) = 𝑢))
231grpoidinvlem4 31091 . . . . . . . . . . . . . 14 (((𝐺 ∈ GrpOp ∧ 𝑤 ∈ 𝑋) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑤) = 𝑢 ∧ (𝑤𝐺𝑦) = 𝑢)) → (𝑤𝐺𝑢) = (𝑢𝐺𝑤))
2422, 23syldan 603 . . . . . . . . . . . . 13 (((𝐺 ∈ GrpOp ∧ 𝑤 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) → (𝑤𝐺𝑢) = (𝑢𝐺𝑤))
2524an32s 665 . . . . . . . . . . . 12 (((𝐺 ∈ GrpOp ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) → (𝑤𝐺𝑢) = (𝑢𝐺𝑤))
2625adantllr 732 . . . . . . . . . . 11 ((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) → (𝑤𝐺𝑢) = (𝑢𝐺𝑤))
2726adantr 486 . . . . . . . . . 10 (((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) ∧ (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥)) → (𝑤𝐺𝑢) = (𝑢𝐺𝑤))
28 oveq2 7420 . . . . . . . . . . . . . . 15 (𝑥 = 𝑢 → (𝑤𝐺𝑥) = (𝑤𝐺𝑢))
29 id 23 . . . . . . . . . . . . . . 15 (𝑥 = 𝑢 → 𝑥 = 𝑢)
3028, 29eqeq12d 2777 . . . . . . . . . . . . . 14 (𝑥 = 𝑢 → ((𝑤𝐺𝑥) = 𝑥 ↔ (𝑤𝐺𝑢) = 𝑢))
3130rspcva 3575 . . . . . . . . . . . . 13 ((𝑢 ∈ 𝑋 ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥) → (𝑤𝐺𝑢) = 𝑢)
3231adantll 727 . . . . . . . . . . . 12 (((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥) → (𝑤𝐺𝑢) = 𝑢)
3332ad2ant2rl 762 . . . . . . . . . . 11 ((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ 𝑤 ∈ 𝑋) ∧ (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥)) → (𝑤𝐺𝑢) = 𝑢)
3433adantllr 732 . . . . . . . . . 10 (((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) ∧ (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥)) → (𝑤𝐺𝑢) = 𝑢)
35 oveq2 7420 . . . . . . . . . . . . 13 (𝑥 = 𝑤 → (𝑢𝐺𝑥) = (𝑢𝐺𝑤))
36 id 23 . . . . . . . . . . . . 13 (𝑥 = 𝑤 → 𝑥 = 𝑤)
3735, 36eqeq12d 2777 . . . . . . . . . . . 12 (𝑥 = 𝑤 → ((𝑢𝐺𝑥) = 𝑥 ↔ (𝑢𝐺𝑤) = 𝑤))
3837rspcva 3575 . . . . . . . . . . 11 ((𝑤 ∈ 𝑋 ∧ ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥) → (𝑢𝐺𝑤) = 𝑤)
3938ad2ant2lr 761 . . . . . . . . . 10 (((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) ∧ (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥)) → (𝑢𝐺𝑤) = 𝑤)
4027, 34, 393eqtr3d 2804 . . . . . . . . 9 (((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) ∧ (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥)) → 𝑢 = 𝑤)
4140ex 418 . . . . . . . 8 ((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) → ((∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥) → 𝑢 = 𝑤))
4211, 41mpand 708 . . . . . . 7 ((((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) ∧ 𝑤 ∈ 𝑋) → (∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥 → 𝑢 = 𝑤))
4342ralrimiva 3155 . . . . . 6 (((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) → ∀𝑤 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥 → 𝑢 = 𝑤))
4410, 43jca 521 . . . . 5 (((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) ∧ ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢))) → (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑤 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥 → 𝑢 = 𝑤)))
4544ex 418 . . . 4 ((𝐺 ∈ GrpOp ∧ 𝑢 ∈ 𝑋) → (∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑤 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥 → 𝑢 = 𝑤))))
4645reximdva 3176 . . 3 (𝐺 ∈ GrpOp → (∃𝑢 ∈ 𝑋 ∀𝑧 ∈ 𝑋 (((𝑢𝐺𝑧) = 𝑧 ∧ (𝑧𝐺𝑢) = 𝑧) ∧ ∃𝑦 ∈ 𝑋 ((𝑦𝐺𝑧) = 𝑢 ∧ (𝑧𝐺𝑦) = 𝑢)) → ∃𝑢 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑤 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥 → 𝑢 = 𝑤))))
472, 46mpd 16 . 2 (𝐺 ∈ GrpOp → ∃𝑢 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑤 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥 → 𝑢 = 𝑤)))
48 oveq1 7419 . . . . 5 (𝑢 = 𝑤 → (𝑢𝐺𝑥) = (𝑤𝐺𝑥))
4948eqeq1d 2763 . . . 4 (𝑢 = 𝑤 → ((𝑢𝐺𝑥) = 𝑥 ↔ (𝑤𝐺𝑥) = 𝑥))
5049ralbidv 3186 . . 3 (𝑢 = 𝑤 → (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ↔ ∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥))
5150reu8 3691 . 2 (∃!𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ↔ ∃𝑢 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥 ∧ ∀𝑤 ∈ 𝑋 (∀𝑥 ∈ 𝑋 (𝑤𝐺𝑥) = 𝑥 → 𝑢 = 𝑤)))
5247, 51sylibr 237 1 (𝐺 ∈ GrpOp → ∃!𝑢 ∈ 𝑋 ∀𝑥 ∈ 𝑋 (𝑢𝐺𝑥) = 𝑥)
Colors of variables:    wff setvar class
This proof depends on syntax axioms:   → wi 4   ∧ wa 401   = wceq 1570   ∈ wcel 2145  ∀wral 3077  ∃wrex 3087  ∃!wreu 3364  ran crn 5652  (class class class)co 7412  GrpOpcgr 31073
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-8 2147  ax-9 2155  ax-10 2178  ax-11 2194  ax-12 2213  ax-ext 2733  ax-sep 5249  ax-nul 5260  ax-pr 5391  ax-un 7740
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1813  df-nf 1817  df-sb 2100  df-mo 2565  df-eu 2595  df-clab 2740  df-cleq 2753  df-clel 2836  df-nfc 2910  df-ne 2957  df-ral 3078  df-rex 3088  df-reu 3367  df-rab 3414  df-v 3453  df-sbc 3740  df-csb 3848  df-dif 3902  df-un 3904  df-in 3906  df-ss 3916  df-nul 4280  df-if 4483  df-sn 4585  df-pr 4587  df-op 4591  df-uni 4868  df-iun 4953  df-br 5104  df-opab 5168  df-mpt 5187  df-id 5546  df-xp 5657  df-rel 5658  df-cnv 5659  df-co 5660  df-dm 5661  df-rn 5662  df-iota 6487  df-fun 6533  df-fn 6534  df-f 6535  df-fo 6537  df-fv 6539  df-ov 7415  df-grpo 31077
This theorem is used by:  grpoidval  31097  grpoidcl  31098  grpoidinv2  31099  cnidOLD  31166  hilid  31745
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