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Mirrors > Home > MPE Home > Th. List > xrs1cmn | Structured version Visualization version GIF version |
Description: The extended real numbers restricted to ℝ* ∖ {-∞} form a commutative monoid. They are not a group because 1 + +∞ = 2 + +∞ even though 1 ≠ 2. (Contributed by Mario Carneiro, 27-Nov-2014.) |
Ref | Expression |
---|---|
xrs1mnd.1 | ⊢ 𝑅 = (ℝ*𝑠 ↾s (ℝ* ∖ {-∞})) |
Ref | Expression |
---|---|
xrs1cmn | ⊢ 𝑅 ∈ CMnd |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | xrs1mnd.1 | . . 3 ⊢ 𝑅 = (ℝ*𝑠 ↾s (ℝ* ∖ {-∞})) | |
2 | 1 | xrs1mnd 21342 | . 2 ⊢ 𝑅 ∈ Mnd |
3 | eldifi 4125 | . . . 4 ⊢ (𝑥 ∈ (ℝ* ∖ {-∞}) → 𝑥 ∈ ℝ*) | |
4 | eldifi 4125 | . . . 4 ⊢ (𝑦 ∈ (ℝ* ∖ {-∞}) → 𝑦 ∈ ℝ*) | |
5 | xaddcom 13257 | . . . 4 ⊢ ((𝑥 ∈ ℝ* ∧ 𝑦 ∈ ℝ*) → (𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥)) | |
6 | 3, 4, 5 | syl2an 594 | . . 3 ⊢ ((𝑥 ∈ (ℝ* ∖ {-∞}) ∧ 𝑦 ∈ (ℝ* ∖ {-∞})) → (𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥)) |
7 | 6 | rgen2 3193 | . 2 ⊢ ∀𝑥 ∈ (ℝ* ∖ {-∞})∀𝑦 ∈ (ℝ* ∖ {-∞})(𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥) |
8 | difss 4130 | . . . 4 ⊢ (ℝ* ∖ {-∞}) ⊆ ℝ* | |
9 | xrsbas 21316 | . . . . 5 ⊢ ℝ* = (Base‘ℝ*𝑠) | |
10 | 1, 9 | ressbas2 17223 | . . . 4 ⊢ ((ℝ* ∖ {-∞}) ⊆ ℝ* → (ℝ* ∖ {-∞}) = (Base‘𝑅)) |
11 | 8, 10 | ax-mp 5 | . . 3 ⊢ (ℝ* ∖ {-∞}) = (Base‘𝑅) |
12 | xrex 13007 | . . . . 5 ⊢ ℝ* ∈ V | |
13 | 12 | difexi 5332 | . . . 4 ⊢ (ℝ* ∖ {-∞}) ∈ V |
14 | xrsadd 21317 | . . . . 5 ⊢ +𝑒 = (+g‘ℝ*𝑠) | |
15 | 1, 14 | ressplusg 17276 | . . . 4 ⊢ ((ℝ* ∖ {-∞}) ∈ V → +𝑒 = (+g‘𝑅)) |
16 | 13, 15 | ax-mp 5 | . . 3 ⊢ +𝑒 = (+g‘𝑅) |
17 | 11, 16 | iscmn 19749 | . 2 ⊢ (𝑅 ∈ CMnd ↔ (𝑅 ∈ Mnd ∧ ∀𝑥 ∈ (ℝ* ∖ {-∞})∀𝑦 ∈ (ℝ* ∖ {-∞})(𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥))) |
18 | 2, 7, 17 | mpbir2an 709 | 1 ⊢ 𝑅 ∈ CMnd |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1533 ∈ wcel 2098 ∀wral 3057 Vcvv 3471 ∖ cdif 3944 ⊆ wss 3947 {csn 4630 ‘cfv 6551 (class class class)co 7424 -∞cmnf 11282 ℝ*cxr 11283 +𝑒 cxad 13128 Basecbs 17185 ↾s cress 17214 +gcplusg 17238 ℝ*𝑠cxrs 17487 Mndcmnd 18699 CMndccmn 19740 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-10 2129 ax-11 2146 ax-12 2166 ax-ext 2698 ax-sep 5301 ax-nul 5308 ax-pow 5367 ax-pr 5431 ax-un 7744 ax-cnex 11200 ax-resscn 11201 ax-1cn 11202 ax-icn 11203 ax-addcl 11204 ax-addrcl 11205 ax-mulcl 11206 ax-mulrcl 11207 ax-mulcom 11208 ax-addass 11209 ax-mulass 11210 ax-distr 11211 ax-i2m1 11212 ax-1ne0 11213 ax-1rid 11214 ax-rnegex 11215 ax-rrecex 11216 ax-cnre 11217 ax-pre-lttri 11218 ax-pre-lttrn 11219 ax-pre-ltadd 11220 ax-pre-mulgt0 11221 |
This theorem depends on definitions: df-bi 206 df-an 395 df-or 846 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2529 df-eu 2558 df-clab 2705 df-cleq 2719 df-clel 2805 df-nfc 2880 df-ne 2937 df-nel 3043 df-ral 3058 df-rex 3067 df-reu 3373 df-rab 3429 df-v 3473 df-sbc 3777 df-csb 3893 df-dif 3950 df-un 3952 df-in 3954 df-ss 3964 df-pss 3966 df-nul 4325 df-if 4531 df-pw 4606 df-sn 4631 df-pr 4633 df-tp 4635 df-op 4637 df-uni 4911 df-iun 5000 df-br 5151 df-opab 5213 df-mpt 5234 df-tr 5268 df-id 5578 df-eprel 5584 df-po 5592 df-so 5593 df-fr 5635 df-we 5637 df-xp 5686 df-rel 5687 df-cnv 5688 df-co 5689 df-dm 5690 df-rn 5691 df-res 5692 df-ima 5693 df-pred 6308 df-ord 6375 df-on 6376 df-lim 6377 df-suc 6378 df-iota 6503 df-fun 6553 df-fn 6554 df-f 6555 df-f1 6556 df-fo 6557 df-f1o 6558 df-fv 6559 df-riota 7380 df-ov 7427 df-oprab 7428 df-mpo 7429 df-om 7875 df-1st 7997 df-2nd 7998 df-frecs 8291 df-wrecs 8322 df-recs 8396 df-rdg 8435 df-1o 8491 df-er 8729 df-en 8969 df-dom 8970 df-sdom 8971 df-fin 8972 df-pnf 11286 df-mnf 11287 df-xr 11288 df-ltxr 11289 df-le 11290 df-sub 11482 df-neg 11483 df-nn 12249 df-2 12311 df-3 12312 df-4 12313 df-5 12314 df-6 12315 df-7 12316 df-8 12317 df-9 12318 df-n0 12509 df-z 12595 df-dec 12714 df-uz 12859 df-xadd 13131 df-fz 13523 df-struct 17121 df-sets 17138 df-slot 17156 df-ndx 17168 df-base 17186 df-ress 17215 df-plusg 17251 df-mulr 17252 df-tset 17257 df-ple 17258 df-ds 17260 df-xrs 17489 df-mgm 18605 df-sgrp 18684 df-mnd 18700 df-cmn 19742 |
This theorem is referenced by: xrge0cmn 21346 imasdsf1olem 24297 gsumge0cl 45761 |
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