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Theorem infltoreq 9508

Description: The infimum of a finite set is less than or equal to all the elements of the set. (Contributed by AV, 4-Sep-2020.)

**Hypotheses**
Ref	Expression
infltoreq.1	⊢ (𝜑 → 𝑅 Or 𝐴)
infltoreq.2	⊢ (𝜑 → 𝐵 ⊆ 𝐴)
infltoreq.3	⊢ (𝜑 → 𝐵 ∈ Fin)
infltoreq.4	⊢ (𝜑 → 𝐶 ∈ 𝐵)
infltoreq.5	⊢ (𝜑 → 𝑆 = inf(𝐵, 𝐴, 𝑅))

**Assertion**
Ref	Expression
infltoreq	⊢ (𝜑 → (𝑆𝑅𝐶 ∨ 𝐶 = 𝑆))

**Proof of Theorem infltoreq**
Step	Hyp	Ref	Expression
1		infltoreq.1	. . . 4 ⊢ (𝜑 → 𝑅 Or 𝐴)
2		cnvso 6274	. . . 4 ⊢ (𝑅 Or 𝐴 ↔ ^◡𝑅 Or 𝐴)
3	1, 2	sylib 218	. . 3 ⊢ (𝜑 → ^◡𝑅 Or 𝐴)
4		infltoreq.2	. . 3 ⊢ (𝜑 → 𝐵 ⊆ 𝐴)
5		infltoreq.3	. . 3 ⊢ (𝜑 → 𝐵 ∈ Fin)
6		infltoreq.4	. . 3 ⊢ (𝜑 → 𝐶 ∈ 𝐵)
7		infltoreq.5	. . . 4 ⊢ (𝜑 → 𝑆 = inf(𝐵, 𝐴, 𝑅))
8		df-inf 9449	. . . 4 ⊢ inf(𝐵, 𝐴, 𝑅) = sup(𝐵, 𝐴, ^◡𝑅)
9	7, 8	eqtrdi 2785	. . 3 ⊢ (𝜑 → 𝑆 = sup(𝐵, 𝐴, ^◡𝑅))
10	3, 4, 5, 6, 9	supgtoreq 9476	. 2 ⊢ (𝜑 → (𝐶^◡𝑅𝑆 ∨ 𝐶 = 𝑆))
11	6	ne0d 4315	. . . . . 6 ⊢ (𝜑 → 𝐵 ≠ ∅)
12		fiinfcl 9507	. . . . . 6 ⊢ ((𝑅 Or 𝐴 ∧ (𝐵 ∈ Fin ∧ 𝐵 ≠ ∅ ∧ 𝐵 ⊆ 𝐴)) → inf(𝐵, 𝐴, 𝑅) ∈ 𝐵)
13	1, 5, 11, 4, 12	syl13anc 1373	. . . . 5 ⊢ (𝜑 → inf(𝐵, 𝐴, 𝑅) ∈ 𝐵)
14	7, 13	eqeltrd 2833	. . . 4 ⊢ (𝜑 → 𝑆 ∈ 𝐵)
15		brcnvg 5856	. . . . 5 ⊢ ((𝐶 ∈ 𝐵 ∧ 𝑆 ∈ 𝐵) → (𝐶^◡𝑅𝑆 ↔ 𝑆𝑅𝐶))
16	15	bicomd 223	. . . 4 ⊢ ((𝐶 ∈ 𝐵 ∧ 𝑆 ∈ 𝐵) → (𝑆𝑅𝐶 ↔ 𝐶^◡𝑅𝑆))
17	6, 14, 16	syl2anc 584	. . 3 ⊢ (𝜑 → (𝑆𝑅𝐶 ↔ 𝐶^◡𝑅𝑆))
18	17	orbi1d 916	. 2 ⊢ (𝜑 → ((𝑆𝑅𝐶 ∨ 𝐶 = 𝑆) ↔ (𝐶^◡𝑅𝑆 ∨ 𝐶 = 𝑆)))
19	10, 18	mpbird 257	1 ⊢ (𝜑 → (𝑆𝑅𝐶 ∨ 𝐶 = 𝑆))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 206 ∧ wa 395 ∨ wo 847 = wceq 1539 ∈ wcel 2107 ≠ wne 2931 ⊆ wss 3924 ∅c0 4306 class class class wbr 5116 Or wor 5557 ^◡ccnv 5650 Fincfn 8953 supcsup 9446 infcinf 9447

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1794 ax-4 1808 ax-5 1909 ax-6 1966 ax-7 2006 ax-8 2109 ax-9 2117 ax-10 2140 ax-11 2156 ax-12 2176 ax-ext 2706 ax-sep 5263 ax-nul 5273 ax-pr 5399 ax-un 7723

This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1542 df-fal 1552 df-ex 1779 df-nf 1783 df-sb 2064 df-mo 2538 df-eu 2567 df-clab 2713 df-cleq 2726 df-clel 2808 df-nfc 2884 df-ne 2932 df-ral 3051 df-rex 3060 df-rmo 3357 df-reu 3358 df-rab 3414 df-v 3459 df-sbc 3764 df-dif 3927 df-un 3929 df-in 3931 df-ss 3941 df-pss 3944 df-nul 4307 df-if 4499 df-pw 4575 df-sn 4600 df-pr 4602 df-op 4606 df-uni 4881 df-br 5117 df-opab 5179 df-tr 5227 df-id 5545 df-eprel 5550 df-po 5558 df-so 5559 df-fr 5603 df-we 5605 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-ord 6352 df-on 6353 df-lim 6354 df-suc 6355 df-iota 6480 df-fun 6529 df-fn 6530 df-f 6531 df-f1 6532 df-fo 6533 df-f1o 6534 df-fv 6535 df-riota 7356 df-om 7856 df-en 8954 df-fin 8957 df-sup 9448 df-inf 9449

This theorem is referenced by: (None)

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