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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 21294 | . 2 ⊢ 𝑅 ∈ Mnd |
3 | eldifi 4121 | . . . 4 ⊢ (𝑥 ∈ (ℝ* ∖ {-∞}) → 𝑥 ∈ ℝ*) | |
4 | eldifi 4121 | . . . 4 ⊢ (𝑦 ∈ (ℝ* ∖ {-∞}) → 𝑦 ∈ ℝ*) | |
5 | xaddcom 13222 | . . . 4 ⊢ ((𝑥 ∈ ℝ* ∧ 𝑦 ∈ ℝ*) → (𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥)) | |
6 | 3, 4, 5 | syl2an 595 | . . 3 ⊢ ((𝑥 ∈ (ℝ* ∖ {-∞}) ∧ 𝑦 ∈ (ℝ* ∖ {-∞})) → (𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥)) |
7 | 6 | rgen2 3191 | . 2 ⊢ ∀𝑥 ∈ (ℝ* ∖ {-∞})∀𝑦 ∈ (ℝ* ∖ {-∞})(𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥) |
8 | difss 4126 | . . . 4 ⊢ (ℝ* ∖ {-∞}) ⊆ ℝ* | |
9 | xrsbas 21268 | . . . . 5 ⊢ ℝ* = (Base‘ℝ*𝑠) | |
10 | 1, 9 | ressbas2 17189 | . . . 4 ⊢ ((ℝ* ∖ {-∞}) ⊆ ℝ* → (ℝ* ∖ {-∞}) = (Base‘𝑅)) |
11 | 8, 10 | ax-mp 5 | . . 3 ⊢ (ℝ* ∖ {-∞}) = (Base‘𝑅) |
12 | xrex 12972 | . . . . 5 ⊢ ℝ* ∈ V | |
13 | 12 | difexi 5321 | . . . 4 ⊢ (ℝ* ∖ {-∞}) ∈ V |
14 | xrsadd 21269 | . . . . 5 ⊢ +𝑒 = (+g‘ℝ*𝑠) | |
15 | 1, 14 | ressplusg 17242 | . . . 4 ⊢ ((ℝ* ∖ {-∞}) ∈ V → +𝑒 = (+g‘𝑅)) |
16 | 13, 15 | ax-mp 5 | . . 3 ⊢ +𝑒 = (+g‘𝑅) |
17 | 11, 16 | iscmn 19707 | . 2 ⊢ (𝑅 ∈ CMnd ↔ (𝑅 ∈ Mnd ∧ ∀𝑥 ∈ (ℝ* ∖ {-∞})∀𝑦 ∈ (ℝ* ∖ {-∞})(𝑥 +𝑒 𝑦) = (𝑦 +𝑒 𝑥))) |
18 | 2, 7, 17 | mpbir2an 708 | 1 ⊢ 𝑅 ∈ CMnd |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1533 ∈ wcel 2098 ∀wral 3055 Vcvv 3468 ∖ cdif 3940 ⊆ wss 3943 {csn 4623 ‘cfv 6536 (class class class)co 7404 -∞cmnf 11247 ℝ*cxr 11248 +𝑒 cxad 13093 Basecbs 17151 ↾s cress 17180 +gcplusg 17204 ℝ*𝑠cxrs 17453 Mndcmnd 18665 CMndccmn 19698 |
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 2163 ax-ext 2697 ax-sep 5292 ax-nul 5299 ax-pow 5356 ax-pr 5420 ax-un 7721 ax-cnex 11165 ax-resscn 11166 ax-1cn 11167 ax-icn 11168 ax-addcl 11169 ax-addrcl 11170 ax-mulcl 11171 ax-mulrcl 11172 ax-mulcom 11173 ax-addass 11174 ax-mulass 11175 ax-distr 11176 ax-i2m1 11177 ax-1ne0 11178 ax-1rid 11179 ax-rnegex 11180 ax-rrecex 11181 ax-cnre 11182 ax-pre-lttri 11183 ax-pre-lttrn 11184 ax-pre-ltadd 11185 ax-pre-mulgt0 11186 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 845 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2528 df-eu 2557 df-clab 2704 df-cleq 2718 df-clel 2804 df-nfc 2879 df-ne 2935 df-nel 3041 df-ral 3056 df-rex 3065 df-reu 3371 df-rab 3427 df-v 3470 df-sbc 3773 df-csb 3889 df-dif 3946 df-un 3948 df-in 3950 df-ss 3960 df-pss 3962 df-nul 4318 df-if 4524 df-pw 4599 df-sn 4624 df-pr 4626 df-tp 4628 df-op 4630 df-uni 4903 df-iun 4992 df-br 5142 df-opab 5204 df-mpt 5225 df-tr 5259 df-id 5567 df-eprel 5573 df-po 5581 df-so 5582 df-fr 5624 df-we 5626 df-xp 5675 df-rel 5676 df-cnv 5677 df-co 5678 df-dm 5679 df-rn 5680 df-res 5681 df-ima 5682 df-pred 6293 df-ord 6360 df-on 6361 df-lim 6362 df-suc 6363 df-iota 6488 df-fun 6538 df-fn 6539 df-f 6540 df-f1 6541 df-fo 6542 df-f1o 6543 df-fv 6544 df-riota 7360 df-ov 7407 df-oprab 7408 df-mpo 7409 df-om 7852 df-1st 7971 df-2nd 7972 df-frecs 8264 df-wrecs 8295 df-recs 8369 df-rdg 8408 df-1o 8464 df-er 8702 df-en 8939 df-dom 8940 df-sdom 8941 df-fin 8942 df-pnf 11251 df-mnf 11252 df-xr 11253 df-ltxr 11254 df-le 11255 df-sub 11447 df-neg 11448 df-nn 12214 df-2 12276 df-3 12277 df-4 12278 df-5 12279 df-6 12280 df-7 12281 df-8 12282 df-9 12283 df-n0 12474 df-z 12560 df-dec 12679 df-uz 12824 df-xadd 13096 df-fz 13488 df-struct 17087 df-sets 17104 df-slot 17122 df-ndx 17134 df-base 17152 df-ress 17181 df-plusg 17217 df-mulr 17218 df-tset 17223 df-ple 17224 df-ds 17226 df-xrs 17455 df-mgm 18571 df-sgrp 18650 df-mnd 18666 df-cmn 19700 |
This theorem is referenced by: xrge0cmn 21298 imasdsf1olem 24230 gsumge0cl 45640 |
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