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Mirrors > Home > MPE Home > Th. List > negnegs | Structured version Visualization version GIF version |
Description: A surreal is equal to the negative of its negative. Theorem 4(ii) of [Conway] p. 17. (Contributed by Scott Fenton, 3-Feb-2025.) |
Ref | Expression |
---|---|
negnegs | ⊢ (𝐴 ∈ No → ( -us ‘( -us ‘𝐴)) = 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | negscl 27490 | . . . 4 ⊢ (𝐴 ∈ No → ( -us ‘𝐴) ∈ No ) | |
2 | 1 | negsidd 27496 | . . 3 ⊢ (𝐴 ∈ No → (( -us ‘𝐴) +s ( -us ‘( -us ‘𝐴))) = 0s ) |
3 | 1 | negscld 27491 | . . . 4 ⊢ (𝐴 ∈ No → ( -us ‘( -us ‘𝐴)) ∈ No ) |
4 | 3, 1 | addscomd 27431 | . . 3 ⊢ (𝐴 ∈ No → (( -us ‘( -us ‘𝐴)) +s ( -us ‘𝐴)) = (( -us ‘𝐴) +s ( -us ‘( -us ‘𝐴)))) |
5 | negsid 27495 | . . 3 ⊢ (𝐴 ∈ No → (𝐴 +s ( -us ‘𝐴)) = 0s ) | |
6 | 2, 4, 5 | 3eqtr4d 2783 | . 2 ⊢ (𝐴 ∈ No → (( -us ‘( -us ‘𝐴)) +s ( -us ‘𝐴)) = (𝐴 +s ( -us ‘𝐴))) |
7 | id 22 | . . 3 ⊢ (𝐴 ∈ No → 𝐴 ∈ No ) | |
8 | 3, 7, 1 | addscan2d 27462 | . 2 ⊢ (𝐴 ∈ No → ((( -us ‘( -us ‘𝐴)) +s ( -us ‘𝐴)) = (𝐴 +s ( -us ‘𝐴)) ↔ ( -us ‘( -us ‘𝐴)) = 𝐴)) |
9 | 6, 8 | mpbid 231 | 1 ⊢ (𝐴 ∈ No → ( -us ‘( -us ‘𝐴)) = 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 = wceq 1542 ∈ wcel 2107 ‘cfv 6540 (class class class)co 7404 No csur 27123 0s c0s 27303 +s cadds 27423 -us cnegs 27474 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1914 ax-6 1972 ax-7 2012 ax-8 2109 ax-9 2117 ax-10 2138 ax-11 2155 ax-12 2172 ax-ext 2704 ax-rep 5284 ax-sep 5298 ax-nul 5305 ax-pow 5362 ax-pr 5426 ax-un 7720 |
This theorem depends on definitions: df-bi 206 df-an 398 df-or 847 df-3or 1089 df-3an 1090 df-tru 1545 df-fal 1555 df-ex 1783 df-nf 1787 df-sb 2069 df-mo 2535 df-eu 2564 df-clab 2711 df-cleq 2725 df-clel 2811 df-nfc 2886 df-ne 2942 df-ral 3063 df-rex 3072 df-rmo 3377 df-reu 3378 df-rab 3434 df-v 3477 df-sbc 3777 df-csb 3893 df-dif 3950 df-un 3952 df-in 3954 df-ss 3964 df-pss 3966 df-nul 4322 df-if 4528 df-pw 4603 df-sn 4628 df-pr 4630 df-tp 4632 df-op 4634 df-ot 4636 df-uni 4908 df-int 4950 df-iun 4998 df-br 5148 df-opab 5210 df-mpt 5231 df-tr 5265 df-id 5573 df-eprel 5579 df-po 5587 df-so 5588 df-fr 5630 df-se 5631 df-we 5632 df-xp 5681 df-rel 5682 df-cnv 5683 df-co 5684 df-dm 5685 df-rn 5686 df-res 5687 df-ima 5688 df-pred 6297 df-ord 6364 df-on 6365 df-suc 6367 df-iota 6492 df-fun 6542 df-fn 6543 df-f 6544 df-f1 6545 df-fo 6546 df-f1o 6547 df-fv 6548 df-riota 7360 df-ov 7407 df-oprab 7408 df-mpo 7409 df-1st 7970 df-2nd 7971 df-frecs 8261 df-wrecs 8292 df-recs 8366 df-1o 8461 df-2o 8462 df-nadd 8661 df-no 27126 df-slt 27127 df-bday 27128 df-sle 27228 df-sslt 27263 df-scut 27265 df-0s 27305 df-made 27322 df-old 27323 df-left 27325 df-right 27326 df-norec 27402 df-norec2 27413 df-adds 27424 df-negs 27476 |
This theorem is referenced by: sltneg 27499 negs11 27503 negsfo 27507 negsbday 27511 negsubsdi2d 27527 mul2negsd 27597 |
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