Theorem infrenegsupex 9553

Description: The infimum of a set of reals 𝐴 is the negative of the supremum of the negatives of its elements. (Contributed by Jim Kingdon, 14-Jan-2022.)

Hypotheses

Ref	Expression
infrenegsupex.ex	⊢ (𝜑 → ∃𝑥 ∈ ℝ (∀𝑦 ∈ 𝐴 ¬ 𝑦 < 𝑥 ∧ ∀𝑦 ∈ ℝ (𝑥 < 𝑦 → ∃𝑧 ∈ 𝐴 𝑧 < 𝑦)))
infrenegsupex.ss	⊢ (𝜑 → 𝐴 ⊆ ℝ)

Assertion

Ref	Expression
infrenegsupex	⊢ (𝜑 → inf(𝐴, ℝ, < ) = -sup({𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴}, ℝ, < ))

Distinct variable groups:   𝑥,𝐴,𝑦,𝑧   𝜑,𝑥,𝑦,𝑧

Proof of Theorem infrenegsupex

Dummy variables 𝑓 𝑔 𝑤 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		lttri3 7999	. . . . . 6 ⊢ ((𝑓 ∈ ℝ ∧ 𝑔 ∈ ℝ) → (𝑓 = 𝑔 ↔ (¬ 𝑓 < 𝑔 ∧ ¬ 𝑔 < 𝑓)))
2	1	adantl 275	. . . . 5 ⊢ ((𝜑 ∧ (𝑓 ∈ ℝ ∧ 𝑔 ∈ ℝ)) → (𝑓 = 𝑔 ↔ (¬ 𝑓 < 𝑔 ∧ ¬ 𝑔 < 𝑓)))
3		infrenegsupex.ex	. . . . 5 ⊢ (𝜑 → ∃𝑥 ∈ ℝ (∀𝑦 ∈ 𝐴 ¬ 𝑦 < 𝑥 ∧ ∀𝑦 ∈ ℝ (𝑥 < 𝑦 → ∃𝑧 ∈ 𝐴 𝑧 < 𝑦)))
4	2, 3	infclti 7000	. . . 4 ⊢ (𝜑 → inf(𝐴, ℝ, < ) ∈ ℝ)
5	4	recnd 7948	. . 3 ⊢ (𝜑 → inf(𝐴, ℝ, < ) ∈ ℂ)
6	5	negnegd 8221	. 2 ⊢ (𝜑 → --inf(𝐴, ℝ, < ) = inf(𝐴, ℝ, < ))
7		negeq 8112	. . . . . . . . 9 ⊢ (𝑤 = 𝑧 → -𝑤 = -𝑧)
8	7	cbvmptv 4085	. . . . . . . 8 ⊢ (𝑤 ∈ ℝ ↦ -𝑤) = (𝑧 ∈ ℝ ↦ -𝑧)
9	8	mptpreima 5104	. . . . . . 7 ⊢ (◡(𝑤 ∈ ℝ ↦ -𝑤) “ 𝐴) = {𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴}
10		eqid 2170	. . . . . . . . . 10 ⊢ (𝑤 ∈ ℝ ↦ -𝑤) = (𝑤 ∈ ℝ ↦ -𝑤)
11	10	negiso 8871	. . . . . . . . 9 ⊢ ((𝑤 ∈ ℝ ↦ -𝑤) Isom < , ◡ < (ℝ, ℝ) ∧ ◡(𝑤 ∈ ℝ ↦ -𝑤) = (𝑤 ∈ ℝ ↦ -𝑤))
12	11	simpri 112	. . . . . . . 8 ⊢ ◡(𝑤 ∈ ℝ ↦ -𝑤) = (𝑤 ∈ ℝ ↦ -𝑤)
13	12	imaeq1i 4950	. . . . . . 7 ⊢ (◡(𝑤 ∈ ℝ ↦ -𝑤) “ 𝐴) = ((𝑤 ∈ ℝ ↦ -𝑤) “ 𝐴)
14	9, 13	eqtr3i 2193	. . . . . 6 ⊢ {𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴} = ((𝑤 ∈ ℝ ↦ -𝑤) “ 𝐴)
15	14	supeq1i 6965	. . . . 5 ⊢ sup({𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴}, ℝ, < ) = sup(((𝑤 ∈ ℝ ↦ -𝑤) “ 𝐴), ℝ, < )
16	11	simpli 110	. . . . . . . . 9 ⊢ (𝑤 ∈ ℝ ↦ -𝑤) Isom < , ◡ < (ℝ, ℝ)
17		isocnv 5790	. . . . . . . . 9 ⊢ ((𝑤 ∈ ℝ ↦ -𝑤) Isom < , ◡ < (ℝ, ℝ) → ◡(𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ))
18	16, 17	ax-mp 5	. . . . . . . 8 ⊢ ◡(𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ)
19		isoeq1 5780	. . . . . . . . 9 ⊢ (◡(𝑤 ∈ ℝ ↦ -𝑤) = (𝑤 ∈ ℝ ↦ -𝑤) → (◡(𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ) ↔ (𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ)))
20	12, 19	ax-mp 5	. . . . . . . 8 ⊢ (◡(𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ) ↔ (𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ))
21	18, 20	mpbi 144	. . . . . . 7 ⊢ (𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ)
22	21	a1i 9	. . . . . 6 ⊢ (𝜑 → (𝑤 ∈ ℝ ↦ -𝑤) Isom ◡ < , < (ℝ, ℝ))
23		infrenegsupex.ss	. . . . . 6 ⊢ (𝜑 → 𝐴 ⊆ ℝ)
24	3	cnvinfex 6995	. . . . . 6 ⊢ (𝜑 → ∃𝑥 ∈ ℝ (∀𝑦 ∈ 𝐴 ¬ 𝑥◡ < 𝑦 ∧ ∀𝑦 ∈ ℝ (𝑦◡ < 𝑥 → ∃𝑧 ∈ 𝐴 𝑦◡ < 𝑧)))
25	2	cnvti 6996	. . . . . 6 ⊢ ((𝜑 ∧ (𝑓 ∈ ℝ ∧ 𝑔 ∈ ℝ)) → (𝑓 = 𝑔 ↔ (¬ 𝑓◡ < 𝑔 ∧ ¬ 𝑔◡ < 𝑓)))
26	22, 23, 24, 25	supisoti 6987	. . . . 5 ⊢ (𝜑 → sup(((𝑤 ∈ ℝ ↦ -𝑤) “ 𝐴), ℝ, < ) = ((𝑤 ∈ ℝ ↦ -𝑤)‘sup(𝐴, ℝ, ◡ < )))
27	15, 26	eqtrid 2215	. . . 4 ⊢ (𝜑 → sup({𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴}, ℝ, < ) = ((𝑤 ∈ ℝ ↦ -𝑤)‘sup(𝐴, ℝ, ◡ < )))
28		df-inf 6962	. . . . . . 7 ⊢ inf(𝐴, ℝ, < ) = sup(𝐴, ℝ, ◡ < )
29	28	eqcomi 2174	. . . . . 6 ⊢ sup(𝐴, ℝ, ◡ < ) = inf(𝐴, ℝ, < )
30	29	fveq2i 5499	. . . . 5 ⊢ ((𝑤 ∈ ℝ ↦ -𝑤)‘sup(𝐴, ℝ, ◡ < )) = ((𝑤 ∈ ℝ ↦ -𝑤)‘inf(𝐴, ℝ, < ))
31		eqidd 2171	. . . . . 6 ⊢ (𝜑 → (𝑤 ∈ ℝ ↦ -𝑤) = (𝑤 ∈ ℝ ↦ -𝑤))
32		negeq 8112	. . . . . . 7 ⊢ (𝑤 = inf(𝐴, ℝ, < ) → -𝑤 = -inf(𝐴, ℝ, < ))
33	32	adantl 275	. . . . . 6 ⊢ ((𝜑 ∧ 𝑤 = inf(𝐴, ℝ, < )) → -𝑤 = -inf(𝐴, ℝ, < ))
34	5	negcld 8217	. . . . . 6 ⊢ (𝜑 → -inf(𝐴, ℝ, < ) ∈ ℂ)
35	31, 33, 4, 34	fvmptd 5577	. . . . 5 ⊢ (𝜑 → ((𝑤 ∈ ℝ ↦ -𝑤)‘inf(𝐴, ℝ, < )) = -inf(𝐴, ℝ, < ))
36	30, 35	eqtrid 2215	. . . 4 ⊢ (𝜑 → ((𝑤 ∈ ℝ ↦ -𝑤)‘sup(𝐴, ℝ, ◡ < )) = -inf(𝐴, ℝ, < ))
37	27, 36	eqtr2d 2204	. . 3 ⊢ (𝜑 → -inf(𝐴, ℝ, < ) = sup({𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴}, ℝ, < ))
38	37	negeqd 8114	. 2 ⊢ (𝜑 → --inf(𝐴, ℝ, < ) = -sup({𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴}, ℝ, < ))
39	6, 38	eqtr3d 2205	1 ⊢ (𝜑 → inf(𝐴, ℝ, < ) = -sup({𝑧 ∈ ℝ ∣ -𝑧 ∈ 𝐴}, ℝ, < ))

Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 103   ↔ wb 104   = wceq 1348   ∈ wcel 2141  ∀wral 2448  ∃wrex 2449  {crab 2452   ⊆ wss 3121   class class class wbr 3989   ↦ cmpt 4050  ^◡ccnv 4610   “ cima 4614  ‘cfv 5198   Isom wiso 5199  supcsup 6959  infcinf 6960  ℂcc 7772  ℝcr 7773   < clt 7954  -cneg 8091

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 609  ax-in2 610  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528  ax-13 2143  ax-14 2144  ax-ext 2152  ax-sep 4107  ax-pow 4160  ax-pr 4194  ax-un 4418  ax-setind 4521  ax-cnex 7865  ax-resscn 7866  ax-1cn 7867  ax-1re 7868  ax-icn 7869  ax-addcl 7870  ax-addrcl 7871  ax-mulcl 7872  ax-addcom 7874  ax-addass 7876  ax-distr 7878  ax-i2m1 7879  ax-0id 7882  ax-rnegex 7883  ax-cnre 7885  ax-pre-ltirr 7886  ax-pre-apti 7889  ax-pre-ltadd 7890

This theorem depends on definitions:  df-bi 116  df-3an 975  df-tru 1351  df-fal 1354  df-nf 1454  df-sb 1756  df-eu 2022  df-mo 2023  df-clab 2157  df-cleq 2163  df-clel 2166  df-nfc 2301  df-ne 2341  df-nel 2436  df-ral 2453  df-rex 2454  df-reu 2455  df-rmo 2456  df-rab 2457  df-v 2732  df-sbc 2956  df-csb 3050  df-dif 3123  df-un 3125  df-in 3127  df-ss 3134  df-pw 3568  df-sn 3589  df-pr 3590  df-op 3592  df-uni 3797  df-br 3990  df-opab 4051  df-mpt 4052  df-id 4278  df-xp 4617  df-rel 4618  df-cnv 4619  df-co 4620  df-dm 4621  df-rn 4622  df-res 4623  df-ima 4624  df-iota 5160  df-fun 5200  df-fn 5201  df-f 5202  df-f1 5203  df-fo 5204  df-f1o 5205  df-fv 5206  df-isom 5207  df-riota 5809  df-ov 5856  df-oprab 5857  df-mpo 5858  df-sup 6961  df-inf 6962  df-pnf 7956  df-mnf 7957  df-ltxr 7959  df-sub 8092  df-neg 8093

This theorem is referenced by:  supminfex  9556  minmax  11193  infssuzcldc  11906