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Mirrors > Home > MPE Home > Th. List > 2irrexpq | Structured version Visualization version GIF version |
Description: There exist irrational numbers 𝑎 and 𝑏 such that (𝑎↑𝑐𝑏) is rational. Statement in the Metamath book, section 1.1.5, footnote 27 on page 17, and the "classical proof" for theorem 1.2 of [Bauer], p. 483. This proof is not acceptable in intuitionistic logic, since it is based on the law of excluded middle: Either ((√‘2)↑𝑐(√‘2)) is rational, in which case (√‘2), being irrational (see sqrt2irr 16244), can be chosen for both 𝑎 and 𝑏, or ((√‘2)↑𝑐(√‘2)) is irrational, in which case ((√‘2)↑𝑐(√‘2)) can be chosen for 𝑎 and (√‘2) for 𝑏, since (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) = 2 is rational. For an alternate proof, which can be used in intuitionistic logic, see 2irrexpqALT 26823. (Contributed by AV, 23-Dec-2022.) |
Ref | Expression |
---|---|
2irrexpq | ⊢ ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | oveq1 7421 | . . . 4 ⊢ (𝑎 = (√‘2) → (𝑎↑𝑐𝑏) = ((√‘2)↑𝑐𝑏)) | |
2 | 1 | eleq1d 2811 | . . 3 ⊢ (𝑎 = (√‘2) → ((𝑎↑𝑐𝑏) ∈ ℚ ↔ ((√‘2)↑𝑐𝑏) ∈ ℚ)) |
3 | oveq2 7422 | . . . 4 ⊢ (𝑏 = (√‘2) → ((√‘2)↑𝑐𝑏) = ((√‘2)↑𝑐(√‘2))) | |
4 | 3 | eleq1d 2811 | . . 3 ⊢ (𝑏 = (√‘2) → (((√‘2)↑𝑐𝑏) ∈ ℚ ↔ ((√‘2)↑𝑐(√‘2)) ∈ ℚ)) |
5 | 2, 4 | rspc2ev 3621 | . 2 ⊢ (((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) → ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ) |
6 | 3ianor 1104 | . . . 4 ⊢ (¬ ((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) ↔ (¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ)) | |
7 | sqrt2irr0 16246 | . . . . . 6 ⊢ (√‘2) ∈ (ℝ ∖ ℚ) | |
8 | 7 | pm2.24i 150 | . . . . 5 ⊢ (¬ (√‘2) ∈ (ℝ ∖ ℚ) → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
9 | 2rp 13025 | . . . . . . . . . 10 ⊢ 2 ∈ ℝ+ | |
10 | rpsqrtcl 15262 | . . . . . . . . . 10 ⊢ (2 ∈ ℝ+ → (√‘2) ∈ ℝ+) | |
11 | 9, 10 | ax-mp 5 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℝ+ |
12 | rpre 13028 | . . . . . . . . . 10 ⊢ ((√‘2) ∈ ℝ+ → (√‘2) ∈ ℝ) | |
13 | rpge0 13033 | . . . . . . . . . 10 ⊢ ((√‘2) ∈ ℝ+ → 0 ≤ (√‘2)) | |
14 | 12, 13, 12 | recxpcld 26745 | . . . . . . . . 9 ⊢ ((√‘2) ∈ ℝ+ → ((√‘2)↑𝑐(√‘2)) ∈ ℝ) |
15 | 11, 14 | ax-mp 5 | . . . . . . . 8 ⊢ ((√‘2)↑𝑐(√‘2)) ∈ ℝ |
16 | 15 | a1i 11 | . . . . . . 7 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → ((√‘2)↑𝑐(√‘2)) ∈ ℝ) |
17 | id 22 | . . . . . . 7 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → ¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) | |
18 | 16, 17 | eldifd 3958 | . . . . . 6 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → ((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ)) |
19 | 7 | a1i 11 | . . . . . 6 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → (√‘2) ∈ (ℝ ∖ ℚ)) |
20 | sqrt2re 16245 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℝ | |
21 | 20 | recni 11267 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℂ |
22 | cxpmul 26710 | . . . . . . . . 9 ⊢ (((√‘2) ∈ ℝ+ ∧ (√‘2) ∈ ℝ ∧ (√‘2) ∈ ℂ) → ((√‘2)↑𝑐((√‘2) · (√‘2))) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2))) | |
23 | 11, 20, 21, 22 | mp3an 1458 | . . . . . . . 8 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) |
24 | 2re 12330 | . . . . . . . . . . 11 ⊢ 2 ∈ ℝ | |
25 | 0le2 12358 | . . . . . . . . . . 11 ⊢ 0 ≤ 2 | |
26 | remsqsqrt 15254 | . . . . . . . . . . 11 ⊢ ((2 ∈ ℝ ∧ 0 ≤ 2) → ((√‘2) · (√‘2)) = 2) | |
27 | 24, 25, 26 | mp2an 690 | . . . . . . . . . 10 ⊢ ((√‘2) · (√‘2)) = 2 |
28 | 27 | oveq2i 7425 | . . . . . . . . 9 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) = ((√‘2)↑𝑐2) |
29 | 2cn 12331 | . . . . . . . . . . 11 ⊢ 2 ∈ ℂ | |
30 | cxpsqrtth 26752 | . . . . . . . . . . 11 ⊢ (2 ∈ ℂ → ((√‘2)↑𝑐2) = 2) | |
31 | 29, 30 | ax-mp 5 | . . . . . . . . . 10 ⊢ ((√‘2)↑𝑐2) = 2 |
32 | 2z 12638 | . . . . . . . . . . 11 ⊢ 2 ∈ ℤ | |
33 | zq 12982 | . . . . . . . . . . 11 ⊢ (2 ∈ ℤ → 2 ∈ ℚ) | |
34 | 32, 33 | ax-mp 5 | . . . . . . . . . 10 ⊢ 2 ∈ ℚ |
35 | 31, 34 | eqeltri 2822 | . . . . . . . . 9 ⊢ ((√‘2)↑𝑐2) ∈ ℚ |
36 | 28, 35 | eqeltri 2822 | . . . . . . . 8 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) ∈ ℚ |
37 | 23, 36 | eqeltrri 2823 | . . . . . . 7 ⊢ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ |
38 | 37 | a1i 11 | . . . . . 6 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ) |
39 | 18, 19, 38 | 3jca 1125 | . . . . 5 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
40 | 8, 8, 39 | 3jaoi 1425 | . . . 4 ⊢ ((¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
41 | 6, 40 | sylbi 216 | . . 3 ⊢ (¬ ((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
42 | oveq1 7421 | . . . . 5 ⊢ (𝑎 = ((√‘2)↑𝑐(√‘2)) → (𝑎↑𝑐𝑏) = (((√‘2)↑𝑐(√‘2))↑𝑐𝑏)) | |
43 | 42 | eleq1d 2811 | . . . 4 ⊢ (𝑎 = ((√‘2)↑𝑐(√‘2)) → ((𝑎↑𝑐𝑏) ∈ ℚ ↔ (((√‘2)↑𝑐(√‘2))↑𝑐𝑏) ∈ ℚ)) |
44 | oveq2 7422 | . . . . 5 ⊢ (𝑏 = (√‘2) → (((√‘2)↑𝑐(√‘2))↑𝑐𝑏) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2))) | |
45 | 44 | eleq1d 2811 | . . . 4 ⊢ (𝑏 = (√‘2) → ((((√‘2)↑𝑐(√‘2))↑𝑐𝑏) ∈ ℚ ↔ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
46 | 43, 45 | rspc2ev 3621 | . . 3 ⊢ ((((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ) → ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ) |
47 | 41, 46 | syl 17 | . 2 ⊢ (¬ ((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) → ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ) |
48 | 5, 47 | pm2.61i 182 | 1 ⊢ ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ∨ w3o 1083 ∧ w3a 1084 = wceq 1534 ∈ wcel 2099 ∃wrex 3060 ∖ cdif 3944 class class class wbr 5144 ‘cfv 6544 (class class class)co 7414 ℂcc 11145 ℝcr 11146 0cc0 11147 · cmul 11152 ≤ cle 11288 2c2 12311 ℤcz 12602 ℚcq 12976 ℝ+crp 13020 √csqrt 15231 ↑𝑐ccxp 26577 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1906 ax-6 1964 ax-7 2004 ax-8 2101 ax-9 2109 ax-10 2130 ax-11 2147 ax-12 2167 ax-ext 2697 ax-rep 5281 ax-sep 5295 ax-nul 5302 ax-pow 5360 ax-pr 5424 ax-un 7736 ax-inf2 9675 ax-cnex 11203 ax-resscn 11204 ax-1cn 11205 ax-icn 11206 ax-addcl 11207 ax-addrcl 11208 ax-mulcl 11209 ax-mulrcl 11210 ax-mulcom 11211 ax-addass 11212 ax-mulass 11213 ax-distr 11214 ax-i2m1 11215 ax-1ne0 11216 ax-1rid 11217 ax-rnegex 11218 ax-rrecex 11219 ax-cnre 11220 ax-pre-lttri 11221 ax-pre-lttrn 11222 ax-pre-ltadd 11223 ax-pre-mulgt0 11224 ax-pre-sup 11225 ax-addf 11226 |
This theorem depends on definitions: df-bi 206 df-an 395 df-or 846 df-3or 1085 df-3an 1086 df-tru 1537 df-fal 1547 df-ex 1775 df-nf 1779 df-sb 2061 df-mo 2529 df-eu 2558 df-clab 2704 df-cleq 2718 df-clel 2803 df-nfc 2878 df-ne 2931 df-nel 3037 df-ral 3052 df-rex 3061 df-rmo 3365 df-reu 3366 df-rab 3421 df-v 3465 df-sbc 3777 df-csb 3893 df-dif 3950 df-un 3952 df-in 3954 df-ss 3964 df-pss 3967 df-nul 4324 df-if 4525 df-pw 4600 df-sn 4625 df-pr 4627 df-tp 4629 df-op 4631 df-uni 4907 df-int 4948 df-iun 4996 df-iin 4997 df-br 5145 df-opab 5207 df-mpt 5228 df-tr 5262 df-id 5571 df-eprel 5577 df-po 5585 df-so 5586 df-fr 5628 df-se 5629 df-we 5630 df-xp 5679 df-rel 5680 df-cnv 5681 df-co 5682 df-dm 5683 df-rn 5684 df-res 5685 df-ima 5686 df-pred 6303 df-ord 6369 df-on 6370 df-lim 6371 df-suc 6372 df-iota 6496 df-fun 6546 df-fn 6547 df-f 6548 df-f1 6549 df-fo 6550 df-f1o 6551 df-fv 6552 df-isom 6553 df-riota 7370 df-ov 7417 df-oprab 7418 df-mpo 7419 df-of 7680 df-om 7867 df-1st 7993 df-2nd 7994 df-supp 8165 df-frecs 8286 df-wrecs 8317 df-recs 8391 df-rdg 8430 df-1o 8486 df-2o 8487 df-er 8724 df-map 8847 df-pm 8848 df-ixp 8917 df-en 8965 df-dom 8966 df-sdom 8967 df-fin 8968 df-fsupp 9397 df-fi 9445 df-sup 9476 df-inf 9477 df-oi 9544 df-card 9973 df-pnf 11289 df-mnf 11290 df-xr 11291 df-ltxr 11292 df-le 11293 df-sub 11485 df-neg 11486 df-div 11911 df-nn 12257 df-2 12319 df-3 12320 df-4 12321 df-5 12322 df-6 12323 df-7 12324 df-8 12325 df-9 12326 df-n0 12517 df-z 12603 df-dec 12722 df-uz 12867 df-q 12977 df-rp 13021 df-xneg 13138 df-xadd 13139 df-xmul 13140 df-ioo 13374 df-ioc 13375 df-ico 13376 df-icc 13377 df-fz 13531 df-fzo 13674 df-fl 13804 df-mod 13882 df-seq 14014 df-exp 14074 df-fac 14284 df-bc 14313 df-hash 14341 df-shft 15065 df-cj 15097 df-re 15098 df-im 15099 df-sqrt 15233 df-abs 15234 df-limsup 15466 df-clim 15483 df-rlim 15484 df-sum 15684 df-ef 16062 df-sin 16064 df-cos 16065 df-pi 16067 df-struct 17142 df-sets 17159 df-slot 17177 df-ndx 17189 df-base 17207 df-ress 17236 df-plusg 17272 df-mulr 17273 df-starv 17274 df-sca 17275 df-vsca 17276 df-ip 17277 df-tset 17278 df-ple 17279 df-ds 17281 df-unif 17282 df-hom 17283 df-cco 17284 df-rest 17430 df-topn 17431 df-0g 17449 df-gsum 17450 df-topgen 17451 df-pt 17452 df-prds 17455 df-xrs 17510 df-qtop 17515 df-imas 17516 df-xps 17518 df-mre 17592 df-mrc 17593 df-acs 17595 df-mgm 18626 df-sgrp 18705 df-mnd 18721 df-submnd 18767 df-mulg 19056 df-cntz 19305 df-cmn 19774 df-psmet 21329 df-xmet 21330 df-met 21331 df-bl 21332 df-mopn 21333 df-fbas 21334 df-fg 21335 df-cnfld 21338 df-top 22882 df-topon 22899 df-topsp 22921 df-bases 22935 df-cld 23009 df-ntr 23010 df-cls 23011 df-nei 23088 df-lp 23126 df-perf 23127 df-cn 23217 df-cnp 23218 df-haus 23305 df-tx 23552 df-hmeo 23745 df-fil 23836 df-fm 23928 df-flim 23929 df-flf 23930 df-xms 24312 df-ms 24313 df-tms 24314 df-cncf 24884 df-limc 25881 df-dv 25882 df-log 26578 df-cxp 26579 |
This theorem is referenced by: (None) |
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