Theorem mndlactfo 33570

Description: An element 𝑋 of a monoid 𝐸 is left-invertible iff its left-translation 𝐹 is surjective. See also grplactf1o 19234. (Contributed by Thierry Arnoux, 3-Aug-2025.)

Hypotheses

Ref	Expression
mndlactfo.b	⊢ 𝐵 = (Base‘𝐸)
mndlactfo.z	⊢ 0 = (0g‘𝐸)
mndlactfo.p	⊢ + = (+g‘𝐸)
mndlactfo.f	⊢ 𝐹 = (𝑎 ∈ 𝐵 ↦ (𝑋 + 𝑎))
mndlactfo.e	⊢ (𝜑 → 𝐸 ∈ Mnd)
mndlactfo.x	⊢ (𝜑 → 𝑋 ∈ 𝐵)

Assertion

Ref	Expression
mndlactfo	⊢ (𝜑 → (𝐹:𝐵–onto→𝐵 ↔ ∃𝑦 ∈ 𝐵 (𝑋 + 𝑦) = 0 ))

Distinct variable groups:   + ,𝑎,𝑦   0 ,𝑎,𝑦   𝐵,𝑎,𝑦   𝐹,𝑎,𝑦   𝑋,𝑎,𝑦   𝜑,𝑎,𝑦

Allowed substitution hints:   𝐸(𝑦, 𝑎)

Proof of Theorem mndlactfo

Dummy variables 𝑧 𝑥 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		simpr 490	. . . 4 ⊢ ((𝜑 ∧ 𝐹:𝐵–onto→𝐵) → 𝐹:𝐵–onto→𝐵)
2		mndlactfo.e	. . . . . 6 ⊢ (𝜑 → 𝐸 ∈ Mnd)
3		mndlactfo.b	. . . . . . 7 ⊢ 𝐵 = (Base‘𝐸)
4		mndlactfo.z	. . . . . . 7 ⊢ 0 = (0g‘𝐸)
5	3, 4	mndidcl 18919	. . . . . 6 ⊢ (𝐸 ∈ Mnd → 0 ∈ 𝐵)
6	2, 5	syl 18	. . . . 5 ⊢ (𝜑 → 0 ∈ 𝐵)
7	6	adantr 486	. . . 4 ⊢ ((𝜑 ∧ 𝐹:𝐵–onto→𝐵) → 0 ∈ 𝐵)
8		foelcdmi 6938	. . . 4 ⊢ ((𝐹:𝐵–onto→𝐵 ∧ 0 ∈ 𝐵) → ∃𝑦 ∈ 𝐵 (𝐹‘𝑦) = 0 )
9	1, 7, 8	syl2anc 596	. . 3 ⊢ ((𝜑 ∧ 𝐹:𝐵–onto→𝐵) → ∃𝑦 ∈ 𝐵 (𝐹‘𝑦) = 0 )
10		mndlactfo.f	. . . . . . 7 ⊢ 𝐹 = (𝑎 ∈ 𝐵 ↦ (𝑋 + 𝑎))
11		oveq2 7420	. . . . . . 7 ⊢ (𝑎 = 𝑦 → (𝑋 + 𝑎) = (𝑋 + 𝑦))
12		simpr 490	. . . . . . 7 ⊢ (((𝜑 ∧ 𝐹:𝐵–onto→𝐵) ∧ 𝑦 ∈ 𝐵) → 𝑦 ∈ 𝐵)
13		ovexd 7447	. . . . . . 7 ⊢ (((𝜑 ∧ 𝐹:𝐵–onto→𝐵) ∧ 𝑦 ∈ 𝐵) → (𝑋 + 𝑦) ∈ V)
14	10, 11, 12, 13	fvmptd3 7009	. . . . . 6 ⊢ (((𝜑 ∧ 𝐹:𝐵–onto→𝐵) ∧ 𝑦 ∈ 𝐵) → (𝐹‘𝑦) = (𝑋 + 𝑦))
15	14	eqeq1d 2763	. . . . 5 ⊢ (((𝜑 ∧ 𝐹:𝐵–onto→𝐵) ∧ 𝑦 ∈ 𝐵) → ((𝐹‘𝑦) = 0 ↔ (𝑋 + 𝑦) = 0 ))
16	15	biimpd 232	. . . 4 ⊢ (((𝜑 ∧ 𝐹:𝐵–onto→𝐵) ∧ 𝑦 ∈ 𝐵) → ((𝐹‘𝑦) = 0 → (𝑋 + 𝑦) = 0 ))
17	16	reximdva 3176	. . 3 ⊢ ((𝜑 ∧ 𝐹:𝐵–onto→𝐵) → (∃𝑦 ∈ 𝐵 (𝐹‘𝑦) = 0 → ∃𝑦 ∈ 𝐵 (𝑋 + 𝑦) = 0 ))
18	9, 17	mpd 16	. 2 ⊢ ((𝜑 ∧ 𝐹:𝐵–onto→𝐵) → ∃𝑦 ∈ 𝐵 (𝑋 + 𝑦) = 0 )
19		mndlactfo.p	. . . . . . 7 ⊢ + = (+g‘𝐸)
20	2	adantr 486	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑎 ∈ 𝐵) → 𝐸 ∈ Mnd)
21		mndlactfo.x	. . . . . . . 8 ⊢ (𝜑 → 𝑋 ∈ 𝐵)
22	21	adantr 486	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑎 ∈ 𝐵) → 𝑋 ∈ 𝐵)
23		simpr 490	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑎 ∈ 𝐵) → 𝑎 ∈ 𝐵)
24	3, 19, 20, 22, 23	mndcld 33565	. . . . . 6 ⊢ ((𝜑 ∧ 𝑎 ∈ 𝐵) → (𝑋 + 𝑎) ∈ 𝐵)
25	24, 10	fmptd 7106	. . . . 5 ⊢ (𝜑 → 𝐹:𝐵⟶𝐵)
26	25	ad2antrr 739	. . . 4 ⊢ (((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) → 𝐹:𝐵⟶𝐵)
27		fveq2 6877	. . . . . . 7 ⊢ (𝑥 = (𝑦 + 𝑧) → (𝐹‘𝑥) = (𝐹‘(𝑦 + 𝑧)))
28	27	eqeq2d 2772	. . . . . 6 ⊢ (𝑥 = (𝑦 + 𝑧) → (𝑧 = (𝐹‘𝑥) ↔ 𝑧 = (𝐹‘(𝑦 + 𝑧))))
29	2	ad3antrrr 743	. . . . . . 7 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → 𝐸 ∈ Mnd)
30		simpllr 788	. . . . . . 7 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → 𝑦 ∈ 𝐵)
31		simpr 490	. . . . . . 7 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → 𝑧 ∈ 𝐵)
32	3, 19, 29, 30, 31	mndcld 33565	. . . . . 6 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → (𝑦 + 𝑧) ∈ 𝐵)
33	21	ad3antrrr 743	. . . . . . . 8 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → 𝑋 ∈ 𝐵)
34	3, 19, 29, 33, 30, 31	mndassd 33566	. . . . . . 7 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → ((𝑋 + 𝑦) + 𝑧) = (𝑋 + (𝑦 + 𝑧)))
35		simplr 781	. . . . . . . . 9 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → (𝑋 + 𝑦) = 0 )
36	35	oveq1d 7427	. . . . . . . 8 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → ((𝑋 + 𝑦) + 𝑧) = ( 0 + 𝑧))
37	3, 19, 4	mndlid 18924	. . . . . . . . 9 ⊢ ((𝐸 ∈ Mnd ∧ 𝑧 ∈ 𝐵) → ( 0 + 𝑧) = 𝑧)
38	29, 31, 37	syl2anc 596	. . . . . . . 8 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → ( 0 + 𝑧) = 𝑧)
39	36, 38	eqtr2d 2797	. . . . . . 7 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → 𝑧 = ((𝑋 + 𝑦) + 𝑧))
40		oveq2 7420	. . . . . . . 8 ⊢ (𝑎 = (𝑦 + 𝑧) → (𝑋 + 𝑎) = (𝑋 + (𝑦 + 𝑧)))
41		ovexd 7447	. . . . . . . 8 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → (𝑋 + (𝑦 + 𝑧)) ∈ V)
42	10, 40, 32, 41	fvmptd3 7009	. . . . . . 7 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → (𝐹‘(𝑦 + 𝑧)) = (𝑋 + (𝑦 + 𝑧)))
43	34, 39, 42	3eqtr4d 2806	. . . . . 6 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → 𝑧 = (𝐹‘(𝑦 + 𝑧)))
44	28, 32, 43	rspcedvdw 3580	. . . . 5 ⊢ ((((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) ∧ 𝑧 ∈ 𝐵) → ∃𝑥 ∈ 𝐵 𝑧 = (𝐹‘𝑥))
45	44	ralrimiva 3155	. . . 4 ⊢ (((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) → ∀𝑧 ∈ 𝐵 ∃𝑥 ∈ 𝐵 𝑧 = (𝐹‘𝑥))
46		dffo3 7094	. . . 4 ⊢ (𝐹:𝐵–onto→𝐵 ↔ (𝐹:𝐵⟶𝐵 ∧ ∀𝑧 ∈ 𝐵 ∃𝑥 ∈ 𝐵 𝑧 = (𝐹‘𝑥)))
47	26, 45, 46	sylanbrc 595	. . 3 ⊢ (((𝜑 ∧ 𝑦 ∈ 𝐵) ∧ (𝑋 + 𝑦) = 0 ) → 𝐹:𝐵–onto→𝐵)
48	47	r19.29an 3167	. 2 ⊢ ((𝜑 ∧ ∃𝑦 ∈ 𝐵 (𝑋 + 𝑦) = 0 ) → 𝐹:𝐵–onto→𝐵)
49	18, 48	impbida 813	1 ⊢ (𝜑 → (𝐹:𝐵–onto→𝐵 ↔ ∃𝑦 ∈ 𝐵 (𝑋 + 𝑦) = 0 ))

This proof depends on syntax axioms:   → wi 4   ↔ wb 209   ∧ wa 401   = wceq 1570   ∈ wcel 2145  ∀wral 3077  ∃wrex 3087  Vcvv 3451   ↦ cmpt 5186  ⟶wf 6527  –onto→wfo 6529  ‘cfv 6531  (class class class)co 7412  Basecbs 17367  +_gcplusg 17408  0_gc0g 17590  Mndcmnd 18903

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

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-rmo 3366  df-reu 3367  df-rab 3414  df-v 3453  df-sbc 3740  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-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-res 5663  df-ima 5664  df-iota 6487  df-fun 6533  df-fn 6534  df-f 6535  df-fo 6537  df-fv 6539  df-riota 7369  df-ov 7415  df-0g 17592  df-mgm 18796  df-sgrp 18888  df-mnd 18904

This theorem is used by:  mndlactf1o  33573