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Theorem xrnepnf 12904

Description: An extended real other than plus infinity is real or negative infinite. (Contributed by Mario Carneiro, 20-Aug-2015.)

**Assertion**
Ref	Expression
xrnepnf	⊢ ((𝐴 ∈ ℝ^* ∧ 𝐴 ≠ +∞) ↔ (𝐴 ∈ ℝ ∨ 𝐴 = -∞))

**Proof of Theorem xrnepnf**
Step	Hyp	Ref	Expression
1		pm5.61 999	. 2 ⊢ ((((𝐴 ∈ ℝ ∨ 𝐴 = -∞) ∨ 𝐴 = +∞) ∧ ¬ 𝐴 = +∞) ↔ ((𝐴 ∈ ℝ ∨ 𝐴 = -∞) ∧ ¬ 𝐴 = +∞))
2		elxr 12902	. . . 4 ⊢ (𝐴 ∈ ℝ^* ↔ (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞))
3		df-3or 1088	. . . 4 ⊢ ((𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞) ↔ ((𝐴 ∈ ℝ ∨ 𝐴 = +∞) ∨ 𝐴 = -∞))
4		or32 924	. . . 4 ⊢ (((𝐴 ∈ ℝ ∨ 𝐴 = +∞) ∨ 𝐴 = -∞) ↔ ((𝐴 ∈ ℝ ∨ 𝐴 = -∞) ∨ 𝐴 = +∞))
5	2, 3, 4	3bitri 297	. . 3 ⊢ (𝐴 ∈ ℝ^* ↔ ((𝐴 ∈ ℝ ∨ 𝐴 = -∞) ∨ 𝐴 = +∞))
6		df-ne 2942	. . 3 ⊢ (𝐴 ≠ +∞ ↔ ¬ 𝐴 = +∞)
7	5, 6	anbi12i 628	. 2 ⊢ ((𝐴 ∈ ℝ^* ∧ 𝐴 ≠ +∞) ↔ (((𝐴 ∈ ℝ ∨ 𝐴 = -∞) ∨ 𝐴 = +∞) ∧ ¬ 𝐴 = +∞))
8		renepnf 11073	. . . . 5 ⊢ (𝐴 ∈ ℝ → 𝐴 ≠ +∞)
9		mnfnepnf 11081	. . . . . 6 ⊢ -∞ ≠ +∞
10		neeq1 3004	. . . . . 6 ⊢ (𝐴 = -∞ → (𝐴 ≠ +∞ ↔ -∞ ≠ +∞))
11	9, 10	mpbiri 258	. . . . 5 ⊢ (𝐴 = -∞ → 𝐴 ≠ +∞)
12	8, 11	jaoi 855	. . . 4 ⊢ ((𝐴 ∈ ℝ ∨ 𝐴 = -∞) → 𝐴 ≠ +∞)
13	12	neneqd 2946	. . 3 ⊢ ((𝐴 ∈ ℝ ∨ 𝐴 = -∞) → ¬ 𝐴 = +∞)
14	13	pm4.71i 561	. 2 ⊢ ((𝐴 ∈ ℝ ∨ 𝐴 = -∞) ↔ ((𝐴 ∈ ℝ ∨ 𝐴 = -∞) ∧ ¬ 𝐴 = +∞))
15	1, 7, 14	3bitr4i 303	1 ⊢ ((𝐴 ∈ ℝ^* ∧ 𝐴 ≠ +∞) ↔ (𝐴 ∈ ℝ ∨ 𝐴 = -∞))

Colors of variables: wff setvar class

Syntax hints: ¬ wn 3 ↔ wb 205 ∧ wa 397 ∨ wo 845 ∨ w3o 1086 = wceq 1539 ∈ wcel 2104 ≠ wne 2941 ℝcr 10920 +∞cpnf 11056 -∞cmnf 11057 ℝ^*cxr 11058

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1911 ax-6 1969 ax-7 2009 ax-8 2106 ax-9 2114 ax-ext 2707 ax-sep 5232 ax-nul 5239 ax-pow 5297 ax-pr 5361 ax-un 7620 ax-cnex 10977 ax-resscn 10978

This theorem depends on definitions: df-bi 206 df-an 398 df-or 846 df-3or 1088 df-tru 1542 df-fal 1552 df-ex 1780 df-sb 2066 df-clab 2714 df-cleq 2728 df-clel 2814 df-ne 2942 df-nel 3048 df-rab 3306 df-v 3439 df-dif 3895 df-un 3897 df-in 3899 df-ss 3909 df-nul 4263 df-pw 4541 df-sn 4566 df-pr 4568 df-uni 4845 df-pnf 11061 df-mnf 11062 df-xr 11063

This theorem is referenced by: xaddnepnf 13021 xlt2addrd 31130 xrlexaddrp 43119 xrnpnfmnf 43243