Theorem poslubmo 18471

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 792	. . . . . 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 5112	. . . . . . . . 9 ⊢ (𝑧 = 𝑤 → (𝑦 ≤ 𝑧 ↔ 𝑦 ≤ 𝑤))
3	2	ralbidv 3187	. . . . . . . 8 ⊢ (𝑧 = 𝑤 → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 ↔ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤))
4		breq2 5112	. . . . . . . 8 ⊢ (𝑧 = 𝑤 → (𝑥 ≤ 𝑧 ↔ 𝑥 ≤ 𝑤))
5	3, 4	imbi12d 347	. . . . . . 7 ⊢ (𝑧 = 𝑤 → ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧) ↔ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤 → 𝑥 ≤ 𝑤)))
6		simprlr 791	. . . . . . 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 789	. . . . . . 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 3581	. . . . . 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 16	. . . . 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 790	. . . . . 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 5112	. . . . . . . . 9 ⊢ (𝑧 = 𝑥 → (𝑦 ≤ 𝑧 ↔ 𝑦 ≤ 𝑥))
12	11	ralbidv 3187	. . . . . . . 8 ⊢ (𝑧 = 𝑥 → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 ↔ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥))
13		breq2 5112	. . . . . . . 8 ⊢ (𝑧 = 𝑥 → (𝑤 ≤ 𝑧 ↔ 𝑤 ≤ 𝑥))
14	12, 13	imbi12d 347	. . . . . . 7 ⊢ (𝑧 = 𝑥 → ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧) ↔ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 → 𝑤 ≤ 𝑥)))
15		simprrr 793	. . . . . . 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 788	. . . . . . 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 3581	. . . . . 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 16	. . . . 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 18381	. . . . . . 7 ⊢ ((𝐾 ∈ Poset ∧ 𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵) → ((𝑥 ≤ 𝑤 ∧ 𝑤 ≤ 𝑥) ↔ 𝑥 = 𝑤))
22	21	3expb 1137	. . . . . 6 ⊢ ((𝐾 ∈ Poset ∧ (𝑥 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) → ((𝑥 ≤ 𝑤 ∧ 𝑤 ≤ 𝑥) ↔ 𝑥 = 𝑤))
23	22	ad4ant13 763	. . . . 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 724	. . . 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 417	. . 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 3207	. 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 5112	. . . . 5 ⊢ (𝑥 = 𝑤 → (𝑦 ≤ 𝑥 ↔ 𝑦 ≤ 𝑤))
28	27	ralbidv 3187	. . . 4 ⊢ (𝑥 = 𝑤 → (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ↔ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑤))
29		breq1 5111	. . . . . 6 ⊢ (𝑥 = 𝑤 → (𝑥 ≤ 𝑧 ↔ 𝑤 ≤ 𝑧))
30	29	imbi2d 343	. . . . 5 ⊢ (𝑥 = 𝑤 → ((∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧) ↔ (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))
31	30	ralbidv 3187	. . . 4 ⊢ (𝑥 = 𝑤 → (∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧) ↔ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑤 ≤ 𝑧)))
32	28, 31	anbi12d 643	. . 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 3692	. 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 237	1 ⊢ ((𝐾 ∈ Poset ∧ 𝑆 ⊆ 𝐵) → ∃*𝑥 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑥 ∧ ∀𝑧 ∈ 𝐵 (∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧 → 𝑥 ≤ 𝑧)))

This proof depends on syntax axioms:   → wi 4   ↔ wb 209   ∧ wa 400   = wceq 1569   ∈ wcel 2142  ∀wral 3078  ∃*wrmo 3367   ⊆ wss 3904   class class class wbr 5108  ‘cfv 6536  Basecbs 17275  lecple 17323  Posetcpo 18369

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1824  ax-4 1838  ax-5 1939  ax-6 1996  ax-7 2037  ax-8 2144  ax-9 2152  ax-ext 2734  ax-nul 5268

This proof depends on definitions:  df-bi 210  df-an 401  df-or 861  df-3an 1104  df-tru 1572  df-fal 1582  df-ex 1809  df-sb 2096  df-mo 2566  df-clab 2741  df-cleq 2754  df-clel 2837  df-ne 2958  df-ral 3079  df-rex 3089  df-rmo 3368  df-rab 3416  df-v 3456  df-sbc 3744  df-dif 3907  df-un 3909  df-ss 3921  df-nul 4286  df-if 4487  df-sn 4589  df-pr 4591  df-op 4595  df-uni 4872  df-br 5109  df-iota 6492  df-fv 6544  df-proset 18356  df-poset 18375

This theorem is used by:  poslubd  18473  lubeldm2  49762