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Mirrors > Home > ILE Home > Th. List > elxr | GIF version |
Description: Membership in the set of extended reals. (Contributed by NM, 14-Oct-2005.) |
Ref | Expression |
---|---|
elxr | ⊢ (𝐴 ∈ ℝ* ↔ (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-xr 7797 | . . 3 ⊢ ℝ* = (ℝ ∪ {+∞, -∞}) | |
2 | 1 | eleq2i 2204 | . 2 ⊢ (𝐴 ∈ ℝ* ↔ 𝐴 ∈ (ℝ ∪ {+∞, -∞})) |
3 | elun 3212 | . 2 ⊢ (𝐴 ∈ (ℝ ∪ {+∞, -∞}) ↔ (𝐴 ∈ ℝ ∨ 𝐴 ∈ {+∞, -∞})) | |
4 | pnfex 7812 | . . . . 5 ⊢ +∞ ∈ V | |
5 | mnfxr 7815 | . . . . . 6 ⊢ -∞ ∈ ℝ* | |
6 | 5 | elexi 2693 | . . . . 5 ⊢ -∞ ∈ V |
7 | 4, 6 | elpr2 3544 | . . . 4 ⊢ (𝐴 ∈ {+∞, -∞} ↔ (𝐴 = +∞ ∨ 𝐴 = -∞)) |
8 | 7 | orbi2i 751 | . . 3 ⊢ ((𝐴 ∈ ℝ ∨ 𝐴 ∈ {+∞, -∞}) ↔ (𝐴 ∈ ℝ ∨ (𝐴 = +∞ ∨ 𝐴 = -∞))) |
9 | 3orass 965 | . . 3 ⊢ ((𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞) ↔ (𝐴 ∈ ℝ ∨ (𝐴 = +∞ ∨ 𝐴 = -∞))) | |
10 | 8, 9 | bitr4i 186 | . 2 ⊢ ((𝐴 ∈ ℝ ∨ 𝐴 ∈ {+∞, -∞}) ↔ (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) |
11 | 2, 3, 10 | 3bitri 205 | 1 ⊢ (𝐴 ∈ ℝ* ↔ (𝐴 ∈ ℝ ∨ 𝐴 = +∞ ∨ 𝐴 = -∞)) |
Colors of variables: wff set class |
Syntax hints: ↔ wb 104 ∨ wo 697 ∨ w3o 961 = wceq 1331 ∈ wcel 1480 ∪ cun 3064 {cpr 3523 ℝcr 7612 +∞cpnf 7790 -∞cmnf 7791 ℝ*cxr 7792 |
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-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-13 1491 ax-14 1492 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2119 ax-sep 4041 ax-pow 4093 ax-un 4350 ax-cnex 7704 |
This theorem depends on definitions: df-bi 116 df-3or 963 df-tru 1334 df-nf 1437 df-sb 1736 df-clab 2124 df-cleq 2130 df-clel 2133 df-nfc 2268 df-rex 2420 df-v 2683 df-un 3070 df-in 3072 df-ss 3079 df-pw 3507 df-sn 3528 df-pr 3529 df-uni 3732 df-pnf 7795 df-mnf 7796 df-xr 7797 |
This theorem is referenced by: xrnemnf 9557 xrnepnf 9558 xrltnr 9559 xrltnsym 9572 xrlttr 9574 xrltso 9575 xrlttri3 9576 nltpnft 9590 npnflt 9591 ngtmnft 9593 nmnfgt 9594 xrrebnd 9595 xnegcl 9608 xnegneg 9609 xltnegi 9611 xrpnfdc 9618 xrmnfdc 9619 xnegid 9635 xaddcom 9637 xaddid1 9638 xnegdi 9644 xleadd1a 9649 xltadd1 9652 xlt2add 9656 xsubge0 9657 xposdif 9658 xleaddadd 9663 qbtwnxr 10028 xrmaxiflemcl 11007 xrmaxifle 11008 xrmaxiflemab 11009 xrmaxiflemlub 11010 xrmaxltsup 11020 xrmaxadd 11023 xrbdtri 11038 isxmet2d 12506 blssioo 12703 |
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