ngtmnft - Metamath Proof Explorer

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Theorem ngtmnft 13081

Description: An extended real is not greater than minus infinity iff they are equal. (Contributed by NM, 2-Feb-2006.)

**Assertion**
Ref	Expression
ngtmnft	⊢ (𝐴 ∈ ℝ^* → (𝐴 = -∞ ↔ ¬ -∞ < 𝐴))

**Proof of Theorem ngtmnft**
Step	Hyp	Ref	Expression
1		mnfxr 11189	. . . 4 ⊢ -∞ ∈ ℝ^*
2		xrltnr 13033	. . . 4 ⊢ (-∞ ∈ ℝ^* → ¬ -∞ < -∞)
3	1, 2	ax-mp 5	. . 3 ⊢ ¬ -∞ < -∞
4		breq2 5102	. . 3 ⊢ (𝐴 = -∞ → (-∞ < 𝐴 ↔ -∞ < -∞))
5	3, 4	mtbiri 327	. 2 ⊢ (𝐴 = -∞ → ¬ -∞ < 𝐴)
6		mnfle 13049	. . . . 5 ⊢ (𝐴 ∈ ℝ^* → -∞ ≤ 𝐴)
7		xrleloe 13058	. . . . . 6 ⊢ ((-∞ ∈ ℝ^* ∧ 𝐴 ∈ ℝ^*) → (-∞ ≤ 𝐴 ↔ (-∞ < 𝐴 ∨ -∞ = 𝐴)))
8	1, 7	mpan 690	. . . . 5 ⊢ (𝐴 ∈ ℝ^* → (-∞ ≤ 𝐴 ↔ (-∞ < 𝐴 ∨ -∞ = 𝐴)))
9	6, 8	mpbid 232	. . . 4 ⊢ (𝐴 ∈ ℝ^* → (-∞ < 𝐴 ∨ -∞ = 𝐴))
10	9	ord 864	. . 3 ⊢ (𝐴 ∈ ℝ^* → (¬ -∞ < 𝐴 → -∞ = 𝐴))
11		eqcom 2743	. . 3 ⊢ (-∞ = 𝐴 ↔ 𝐴 = -∞)
12	10, 11	imbitrdi 251	. 2 ⊢ (𝐴 ∈ ℝ^* → (¬ -∞ < 𝐴 → 𝐴 = -∞))
13	5, 12	impbid2 226	1 ⊢ (𝐴 ∈ ℝ^* → (𝐴 = -∞ ↔ ¬ -∞ < 𝐴))

Colors of variables: wff setvar class

Syntax hints: ¬ wn 3 → wi 4 ↔ wb 206 ∨ wo 847 = wceq 1541 ∈ wcel 2113 class class class wbr 5098 -∞cmnf 11164 ℝ^*cxr 11165 < clt 11166 ≤ cle 11167

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1968 ax-7 2009 ax-8 2115 ax-9 2123 ax-10 2146 ax-11 2162 ax-12 2184 ax-ext 2708 ax-sep 5241 ax-nul 5251 ax-pow 5310 ax-pr 5377 ax-un 7680 ax-cnex 11082 ax-resscn 11083 ax-pre-lttri 11100 ax-pre-lttrn 11101

This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1544 df-fal 1554 df-ex 1781 df-nf 1785 df-sb 2068 df-mo 2539 df-eu 2569 df-clab 2715 df-cleq 2728 df-clel 2811 df-nfc 2885 df-ne 2933 df-nel 3037 df-ral 3052 df-rex 3061 df-rab 3400 df-v 3442 df-sbc 3741 df-csb 3850 df-dif 3904 df-un 3906 df-in 3908 df-ss 3918 df-nul 4286 df-if 4480 df-pw 4556 df-sn 4581 df-pr 4583 df-op 4587 df-uni 4864 df-br 5099 df-opab 5161 df-mpt 5180 df-id 5519 df-po 5532 df-so 5533 df-xp 5630 df-rel 5631 df-cnv 5632 df-co 5633 df-dm 5634 df-rn 5635 df-res 5636 df-ima 5637 df-iota 6448 df-fun 6494 df-fn 6495 df-f 6496 df-f1 6497 df-fo 6498 df-f1o 6499 df-fv 6500 df-er 8635 df-en 8884 df-dom 8885 df-sdom 8886 df-pnf 11168 df-mnf 11169 df-xr 11170 df-ltxr 11171 df-le 11172

This theorem is referenced by: xlemnf 13082 xrrebnd 13083 ge0nemnf 13088 xlt2add 13175 xrsdsreclblem 21367 xblpnfps 24339 xblpnf 24340 supxrnemnf 32848 itg2addnclem 37872 supxrgelem 45582 supxrge 45583 nemnftgtmnft 45589 infxrbnd2 45613

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