poslubmo - Metamath Proof Explorer

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Theorem poslubmo 18376

Description: Least upper bounds in a poset are unique if they exist. (Contributed by Stefan O'Rear, 31-Jan-2015.) (Revised by NM, 16-Jun-2017.)

**Hypotheses**
Ref	Expression
poslubmo.l	⊢ ≤ = (le‘𝐾)
poslubmo.b	⊢ 𝐵 = (Base‘𝐾)

**Assertion**
Ref	Expression
poslubmo	⊢ ((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) → ∃*𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)))

Distinct variable groups: 𝑥, ≤ ,𝑦,𝑧 𝑥,𝐵,𝑦,𝑧 𝑥,𝐾,𝑦,𝑧 𝑥,𝑆,𝑦,𝑧

Proof of Theorem poslubmo Dummy variable 𝑤 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		simprrl 778	. . . . . 6 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤)
2		breq2 5145	. . . . . . . . 9 ⊢ (𝑧 = 𝑤 → (𝑦 ≤ 𝑧 ↔ 𝑦 ≤ 𝑤))
3	2	ralbidv 3171	. . . . . . . 8 ⊢ (𝑧 = 𝑤 → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 ↔ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤))
4		breq2 5145	. . . . . . . 8 ⊢ (𝑧 = 𝑤 → (𝑥 ≤ 𝑧 ↔ 𝑥 ≤ 𝑤))
5	3, 4	imbi12d 344	. . . . . . 7 ⊢ (𝑧 = 𝑤 → ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧) ↔ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 → 𝑥 ≤ 𝑤)))
6		simprlr 777	. . . . . . 7 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧))
7		simplrr 775	. . . . . . 7 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → 𝑤 ∈ 𝐵)
8	5, 6, 7	rspcdva 3607	. . . . . 6 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 → 𝑥 ≤ 𝑤))
9	1, 8	mpd 15	. . . . 5 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → 𝑥 ≤ 𝑤)
10		simprll 776	. . . . . 6 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥)
11		breq2 5145	. . . . . . . . 9 ⊢ (𝑧 = 𝑥 → (𝑦 ≤ 𝑧 ↔ 𝑦 ≤ 𝑥))
12	11	ralbidv 3171	. . . . . . . 8 ⊢ (𝑧 = 𝑥 → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 ↔ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥))
13		breq2 5145	. . . . . . . 8 ⊢ (𝑧 = 𝑥 → (𝑤 ≤ 𝑧 ↔ 𝑤 ≤ 𝑥))
14	12, 13	imbi12d 344	. . . . . . 7 ⊢ (𝑧 = 𝑥 → ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧) ↔ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 → 𝑤 ≤ 𝑥)))
15		simprrr 779	. . . . . . 7 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧))
16		simplrl 774	. . . . . . 7 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → 𝑥 ∈ 𝐵)
17	14, 15, 16	rspcdva 3607	. . . . . 6 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 → 𝑤 ≤ 𝑥))
18	10, 17	mpd 15	. . . . 5 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → 𝑤 ≤ 𝑥)
19		poslubmo.b	. . . . . . . 8 ⊢ 𝐵 = (Base‘𝐾)
20		poslubmo.l	. . . . . . . 8 ⊢ ≤ = (le‘𝐾)
21	19, 20	posasymb 18284	. . . . . . 7 ⊢ ((𝐾 ∈ Poset ∧ 𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵) → ((𝑥 ≤ 𝑤 ∧ 𝑤 ≤ 𝑥) ↔ 𝑥 = 𝑤))
22	21	3expb 1117	. . . . . 6 ⊢ ((𝐾 ∈ Poset ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) → ((𝑥 ≤ 𝑤 ∧ 𝑤 ≤ 𝑥) ↔ 𝑥 = 𝑤))
23	22	ad4ant13 748	. . . . 5 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → ((𝑥 ≤ 𝑤 ∧ 𝑤 ≤ 𝑥) ↔ 𝑥 = 𝑤))
24	9, 18, 23	mpbi2and 709	. . . 4 ⊢ ((((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) ∧ ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))) → 𝑥 = 𝑤)
25	24	ex 412	. . 3 ⊢ (((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) → (((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧))) → 𝑥 = 𝑤))
26	25	ralrimivva 3194	. 2 ⊢ ((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) → ∀𝑥 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧))) → 𝑥 = 𝑤))
27		breq2 5145	. . . . 5 ⊢ (𝑥 = 𝑤 → (𝑦 ≤ 𝑥 ↔ 𝑦 ≤ 𝑤))
28	27	ralbidv 3171	. . . 4 ⊢ (𝑥 = 𝑤 → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ↔ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤))
29		breq1 5144	. . . . . 6 ⊢ (𝑥 = 𝑤 → (𝑥 ≤ 𝑧 ↔ 𝑤 ≤ 𝑧))
30	29	imbi2d 340	. . . . 5 ⊢ (𝑥 = 𝑤 → ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧) ↔ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))
31	30	ralbidv 3171	. . . 4 ⊢ (𝑥 = 𝑤 → (∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧) ↔ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))
32	28, 31	anbi12d 630	. . 3 ⊢ (𝑥 = 𝑤 → ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ↔ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧))))
33	32	rmo4 3721	. 2 ⊢ (∃*𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ↔ ∀𝑥 ∈ 𝐵 ∀𝑤 ∈ 𝐵 (((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)) ∧ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧))) → 𝑥 = 𝑤))
34	26, 33	sylibr 233	1 ⊢ ((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) → ∃*𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 205 ∧ wa 395 = wceq 1533 ∈ wcel 2098 ∀wral 3055 ∃*wrmo 3369 ⊆ wss 3943 class class class wbr 5141 ‘cfv 6537 Basecbs 17153 lecple 17213 Posetcpo 18272

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-ext 2697 ax-nul 5299

This theorem depends on definitions: df-bi 206 df-an 396 df-or 845 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-sb 2060 df-mo 2528 df-clab 2704 df-cleq 2718 df-clel 2804 df-ne 2935 df-ral 3056 df-rex 3065 df-rmo 3370 df-rab 3427 df-v 3470 df-sbc 3773 df-dif 3946 df-un 3948 df-in 3950 df-ss 3960 df-nul 4318 df-if 4524 df-sn 4624 df-pr 4626 df-op 4630 df-uni 4903 df-br 5142 df-iota 6489 df-fv 6545 df-proset 18260 df-poset 18278

This theorem is referenced by: poslubd 18378 lubeldm2 47860

W3C validator