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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 15353), 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 24941. (Contributed by AV, 23-Dec-2022.) |
Ref | Expression |
---|---|
2irrexpq | ⊢ ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | oveq1 6913 | . . . 4 ⊢ (𝑎 = (√‘2) → (𝑎↑𝑐𝑏) = ((√‘2)↑𝑐𝑏)) | |
2 | 1 | eleq1d 2892 | . . 3 ⊢ (𝑎 = (√‘2) → ((𝑎↑𝑐𝑏) ∈ ℚ ↔ ((√‘2)↑𝑐𝑏) ∈ ℚ)) |
3 | oveq2 6914 | . . . 4 ⊢ (𝑏 = (√‘2) → ((√‘2)↑𝑐𝑏) = ((√‘2)↑𝑐(√‘2))) | |
4 | 3 | eleq1d 2892 | . . 3 ⊢ (𝑏 = (√‘2) → (((√‘2)↑𝑐𝑏) ∈ ℚ ↔ ((√‘2)↑𝑐(√‘2)) ∈ ℚ)) |
5 | 2, 4 | rspc2ev 3542 | . 2 ⊢ (((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) → ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ) |
6 | 3ianor 1138 | . . . 4 ⊢ (¬ ((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) ↔ (¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ)) | |
7 | sqrt2irr0 15355 | . . . . . 6 ⊢ (√‘2) ∈ (ℝ ∖ ℚ) | |
8 | 7 | pm2.24i 148 | . . . . 5 ⊢ (¬ (√‘2) ∈ (ℝ ∖ ℚ) → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
9 | 2rp 12118 | . . . . . . . . . 10 ⊢ 2 ∈ ℝ+ | |
10 | rpsqrtcl 14383 | . . . . . . . . . 10 ⊢ (2 ∈ ℝ+ → (√‘2) ∈ ℝ+) | |
11 | 9, 10 | ax-mp 5 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℝ+ |
12 | rpre 12121 | . . . . . . . . . 10 ⊢ ((√‘2) ∈ ℝ+ → (√‘2) ∈ ℝ) | |
13 | rpge0 12128 | . . . . . . . . . 10 ⊢ ((√‘2) ∈ ℝ+ → 0 ≤ (√‘2)) | |
14 | 12, 13, 12 | recxpcld 24869 | . . . . . . . . 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 3810 | . . . . . 6 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → ((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ)) |
19 | 7 | a1i 11 | . . . . . 6 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → (√‘2) ∈ (ℝ ∖ ℚ)) |
20 | sqrt2re 15354 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℝ | |
21 | 20 | recni 10372 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℂ |
22 | cxpmul 24834 | . . . . . . . . 9 ⊢ (((√‘2) ∈ ℝ+ ∧ (√‘2) ∈ ℝ ∧ (√‘2) ∈ ℂ) → ((√‘2)↑𝑐((√‘2) · (√‘2))) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2))) | |
23 | 11, 20, 21, 22 | mp3an 1591 | . . . . . . . 8 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) |
24 | 2re 11426 | . . . . . . . . . . 11 ⊢ 2 ∈ ℝ | |
25 | 0le2 11461 | . . . . . . . . . . 11 ⊢ 0 ≤ 2 | |
26 | remsqsqrt 14375 | . . . . . . . . . . 11 ⊢ ((2 ∈ ℝ ∧ 0 ≤ 2) → ((√‘2) · (√‘2)) = 2) | |
27 | 24, 25, 26 | mp2an 685 | . . . . . . . . . 10 ⊢ ((√‘2) · (√‘2)) = 2 |
28 | 27 | oveq2i 6917 | . . . . . . . . 9 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) = ((√‘2)↑𝑐2) |
29 | 2cn 11427 | . . . . . . . . . . 11 ⊢ 2 ∈ ℂ | |
30 | cxpsqrtth 24875 | . . . . . . . . . . 11 ⊢ (2 ∈ ℂ → ((√‘2)↑𝑐2) = 2) | |
31 | 29, 30 | ax-mp 5 | . . . . . . . . . 10 ⊢ ((√‘2)↑𝑐2) = 2 |
32 | 2z 11738 | . . . . . . . . . . 11 ⊢ 2 ∈ ℤ | |
33 | zq 12078 | . . . . . . . . . . 11 ⊢ (2 ∈ ℤ → 2 ∈ ℚ) | |
34 | 32, 33 | ax-mp 5 | . . . . . . . . . 10 ⊢ 2 ∈ ℚ |
35 | 31, 34 | eqeltri 2903 | . . . . . . . . 9 ⊢ ((√‘2)↑𝑐2) ∈ ℚ |
36 | 28, 35 | eqeltri 2903 | . . . . . . . 8 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) ∈ ℚ |
37 | 23, 36 | eqeltrri 2904 | . . . . . . 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 1164 | . . . . 5 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
40 | 8, 8, 39 | 3jaoi 1558 | . . . 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 209 | . . 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 6913 | . . . . 5 ⊢ (𝑎 = ((√‘2)↑𝑐(√‘2)) → (𝑎↑𝑐𝑏) = (((√‘2)↑𝑐(√‘2))↑𝑐𝑏)) | |
43 | 42 | eleq1d 2892 | . . . 4 ⊢ (𝑎 = ((√‘2)↑𝑐(√‘2)) → ((𝑎↑𝑐𝑏) ∈ ℚ ↔ (((√‘2)↑𝑐(√‘2))↑𝑐𝑏) ∈ ℚ)) |
44 | oveq2 6914 | . . . . 5 ⊢ (𝑏 = (√‘2) → (((√‘2)↑𝑐(√‘2))↑𝑐𝑏) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2))) | |
45 | 44 | eleq1d 2892 | . . . 4 ⊢ (𝑏 = (√‘2) → ((((√‘2)↑𝑐(√‘2))↑𝑐𝑏) ∈ ℚ ↔ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
46 | 43, 45 | rspc2ev 3542 | . . 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 177 | 1 ⊢ ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ∨ w3o 1112 ∧ w3a 1113 = wceq 1658 ∈ wcel 2166 ∃wrex 3119 ∖ cdif 3796 class class class wbr 4874 ‘cfv 6124 (class class class)co 6906 ℂcc 10251 ℝcr 10252 0cc0 10253 · cmul 10258 ≤ cle 10393 2c2 11407 ℤcz 11705 ℚcq 12072 ℝ+crp 12113 √csqrt 14351 ↑𝑐ccxp 24702 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1896 ax-4 1910 ax-5 2011 ax-6 2077 ax-7 2114 ax-8 2168 ax-9 2175 ax-10 2194 ax-11 2209 ax-12 2222 ax-13 2391 ax-ext 2804 ax-rep 4995 ax-sep 5006 ax-nul 5014 ax-pow 5066 ax-pr 5128 ax-un 7210 ax-inf2 8816 ax-cnex 10309 ax-resscn 10310 ax-1cn 10311 ax-icn 10312 ax-addcl 10313 ax-addrcl 10314 ax-mulcl 10315 ax-mulrcl 10316 ax-mulcom 10317 ax-addass 10318 ax-mulass 10319 ax-distr 10320 ax-i2m1 10321 ax-1ne0 10322 ax-1rid 10323 ax-rnegex 10324 ax-rrecex 10325 ax-cnre 10326 ax-pre-lttri 10327 ax-pre-lttrn 10328 ax-pre-ltadd 10329 ax-pre-mulgt0 10330 ax-pre-sup 10331 ax-addf 10332 ax-mulf 10333 |
This theorem depends on definitions: df-bi 199 df-an 387 df-or 881 df-3or 1114 df-3an 1115 df-tru 1662 df-fal 1672 df-ex 1881 df-nf 1885 df-sb 2070 df-mo 2606 df-eu 2641 df-clab 2813 df-cleq 2819 df-clel 2822 df-nfc 2959 df-ne 3001 df-nel 3104 df-ral 3123 df-rex 3124 df-reu 3125 df-rmo 3126 df-rab 3127 df-v 3417 df-sbc 3664 df-csb 3759 df-dif 3802 df-un 3804 df-in 3806 df-ss 3813 df-pss 3815 df-nul 4146 df-if 4308 df-pw 4381 df-sn 4399 df-pr 4401 df-tp 4403 df-op 4405 df-uni 4660 df-int 4699 df-iun 4743 df-iin 4744 df-br 4875 df-opab 4937 df-mpt 4954 df-tr 4977 df-id 5251 df-eprel 5256 df-po 5264 df-so 5265 df-fr 5302 df-se 5303 df-we 5304 df-xp 5349 df-rel 5350 df-cnv 5351 df-co 5352 df-dm 5353 df-rn 5354 df-res 5355 df-ima 5356 df-pred 5921 df-ord 5967 df-on 5968 df-lim 5969 df-suc 5970 df-iota 6087 df-fun 6126 df-fn 6127 df-f 6128 df-f1 6129 df-fo 6130 df-f1o 6131 df-fv 6132 df-isom 6133 df-riota 6867 df-ov 6909 df-oprab 6910 df-mpt2 6911 df-of 7158 df-om 7328 df-1st 7429 df-2nd 7430 df-supp 7561 df-wrecs 7673 df-recs 7735 df-rdg 7773 df-1o 7827 df-2o 7828 df-oadd 7831 df-er 8010 df-map 8125 df-pm 8126 df-ixp 8177 df-en 8224 df-dom 8225 df-sdom 8226 df-fin 8227 df-fsupp 8546 df-fi 8587 df-sup 8618 df-inf 8619 df-oi 8685 df-card 9079 df-cda 9306 df-pnf 10394 df-mnf 10395 df-xr 10396 df-ltxr 10397 df-le 10398 df-sub 10588 df-neg 10589 df-div 11011 df-nn 11352 df-2 11415 df-3 11416 df-4 11417 df-5 11418 df-6 11419 df-7 11420 df-8 11421 df-9 11422 df-n0 11620 df-z 11706 df-dec 11823 df-uz 11970 df-q 12073 df-rp 12114 df-xneg 12233 df-xadd 12234 df-xmul 12235 df-ioo 12468 df-ioc 12469 df-ico 12470 df-icc 12471 df-fz 12621 df-fzo 12762 df-fl 12889 df-mod 12965 df-seq 13097 df-exp 13156 df-fac 13355 df-bc 13384 df-hash 13412 df-shft 14185 df-cj 14217 df-re 14218 df-im 14219 df-sqrt 14353 df-abs 14354 df-limsup 14580 df-clim 14597 df-rlim 14598 df-sum 14795 df-ef 15171 df-sin 15173 df-cos 15174 df-pi 15176 df-struct 16225 df-ndx 16226 df-slot 16227 df-base 16229 df-sets 16230 df-ress 16231 df-plusg 16319 df-mulr 16320 df-starv 16321 df-sca 16322 df-vsca 16323 df-ip 16324 df-tset 16325 df-ple 16326 df-ds 16328 df-unif 16329 df-hom 16330 df-cco 16331 df-rest 16437 df-topn 16438 df-0g 16456 df-gsum 16457 df-topgen 16458 df-pt 16459 df-prds 16462 df-xrs 16516 df-qtop 16521 df-imas 16522 df-xps 16524 df-mre 16600 df-mrc 16601 df-acs 16603 df-mgm 17596 df-sgrp 17638 df-mnd 17649 df-submnd 17690 df-mulg 17896 df-cntz 18101 df-cmn 18549 df-psmet 20099 df-xmet 20100 df-met 20101 df-bl 20102 df-mopn 20103 df-fbas 20104 df-fg 20105 df-cnfld 20108 df-top 21070 df-topon 21087 df-topsp 21109 df-bases 21122 df-cld 21195 df-ntr 21196 df-cls 21197 df-nei 21274 df-lp 21312 df-perf 21313 df-cn 21403 df-cnp 21404 df-haus 21491 df-tx 21737 df-hmeo 21930 df-fil 22021 df-fm 22113 df-flim 22114 df-flf 22115 df-xms 22496 df-ms 22497 df-tms 22498 df-cncf 23052 df-limc 24030 df-dv 24031 df-log 24703 df-cxp 24704 |
This theorem is referenced by: (None) |
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