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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 15597), 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 25376. (Contributed by AV, 23-Dec-2022.) |
Ref | Expression |
---|---|
2irrexpq | ⊢ ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | oveq1 7156 | . . . 4 ⊢ (𝑎 = (√‘2) → (𝑎↑𝑐𝑏) = ((√‘2)↑𝑐𝑏)) | |
2 | 1 | eleq1d 2896 | . . 3 ⊢ (𝑎 = (√‘2) → ((𝑎↑𝑐𝑏) ∈ ℚ ↔ ((√‘2)↑𝑐𝑏) ∈ ℚ)) |
3 | oveq2 7157 | . . . 4 ⊢ (𝑏 = (√‘2) → ((√‘2)↑𝑐𝑏) = ((√‘2)↑𝑐(√‘2))) | |
4 | 3 | eleq1d 2896 | . . 3 ⊢ (𝑏 = (√‘2) → (((√‘2)↑𝑐𝑏) ∈ ℚ ↔ ((√‘2)↑𝑐(√‘2)) ∈ ℚ)) |
5 | 2, 4 | rspc2ev 3632 | . 2 ⊢ (((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) → ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ) |
6 | 3ianor 1102 | . . . 4 ⊢ (¬ ((√‘2) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ ((√‘2)↑𝑐(√‘2)) ∈ ℚ) ↔ (¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ (√‘2) ∈ (ℝ ∖ ℚ) ∨ ¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ)) | |
7 | sqrt2irr0 15599 | . . . . . 6 ⊢ (√‘2) ∈ (ℝ ∖ ℚ) | |
8 | 7 | pm2.24i 153 | . . . . 5 ⊢ (¬ (√‘2) ∈ (ℝ ∖ ℚ) → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
9 | 2rp 12388 | . . . . . . . . . 10 ⊢ 2 ∈ ℝ+ | |
10 | rpsqrtcl 14619 | . . . . . . . . . 10 ⊢ (2 ∈ ℝ+ → (√‘2) ∈ ℝ+) | |
11 | 9, 10 | ax-mp 5 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℝ+ |
12 | rpre 12391 | . . . . . . . . . 10 ⊢ ((√‘2) ∈ ℝ+ → (√‘2) ∈ ℝ) | |
13 | rpge0 12396 | . . . . . . . . . 10 ⊢ ((√‘2) ∈ ℝ+ → 0 ≤ (√‘2)) | |
14 | 12, 13, 12 | recxpcld 25304 | . . . . . . . . 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 3940 | . . . . . 6 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → ((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ)) |
19 | 7 | a1i 11 | . . . . . 6 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → (√‘2) ∈ (ℝ ∖ ℚ)) |
20 | sqrt2re 15598 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℝ | |
21 | 20 | recni 10648 | . . . . . . . . 9 ⊢ (√‘2) ∈ ℂ |
22 | cxpmul 25269 | . . . . . . . . 9 ⊢ (((√‘2) ∈ ℝ+ ∧ (√‘2) ∈ ℝ ∧ (√‘2) ∈ ℂ) → ((√‘2)↑𝑐((√‘2) · (√‘2))) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2))) | |
23 | 11, 20, 21, 22 | mp3an 1456 | . . . . . . . 8 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) |
24 | 2re 11705 | . . . . . . . . . . 11 ⊢ 2 ∈ ℝ | |
25 | 0le2 11733 | . . . . . . . . . . 11 ⊢ 0 ≤ 2 | |
26 | remsqsqrt 14611 | . . . . . . . . . . 11 ⊢ ((2 ∈ ℝ ∧ 0 ≤ 2) → ((√‘2) · (√‘2)) = 2) | |
27 | 24, 25, 26 | mp2an 690 | . . . . . . . . . 10 ⊢ ((√‘2) · (√‘2)) = 2 |
28 | 27 | oveq2i 7160 | . . . . . . . . 9 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) = ((√‘2)↑𝑐2) |
29 | 2cn 11706 | . . . . . . . . . . 11 ⊢ 2 ∈ ℂ | |
30 | cxpsqrtth 25310 | . . . . . . . . . . 11 ⊢ (2 ∈ ℂ → ((√‘2)↑𝑐2) = 2) | |
31 | 29, 30 | ax-mp 5 | . . . . . . . . . 10 ⊢ ((√‘2)↑𝑐2) = 2 |
32 | 2z 12008 | . . . . . . . . . . 11 ⊢ 2 ∈ ℤ | |
33 | zq 12348 | . . . . . . . . . . 11 ⊢ (2 ∈ ℤ → 2 ∈ ℚ) | |
34 | 32, 33 | ax-mp 5 | . . . . . . . . . 10 ⊢ 2 ∈ ℚ |
35 | 31, 34 | eqeltri 2908 | . . . . . . . . 9 ⊢ ((√‘2)↑𝑐2) ∈ ℚ |
36 | 28, 35 | eqeltri 2908 | . . . . . . . 8 ⊢ ((√‘2)↑𝑐((√‘2) · (√‘2))) ∈ ℚ |
37 | 23, 36 | eqeltrri 2909 | . . . . . . 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 1123 | . . . . 5 ⊢ (¬ ((√‘2)↑𝑐(√‘2)) ∈ ℚ → (((√‘2)↑𝑐(√‘2)) ∈ (ℝ ∖ ℚ) ∧ (√‘2) ∈ (ℝ ∖ ℚ) ∧ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
40 | 8, 8, 39 | 3jaoi 1422 | . . . 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 219 | . . 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 7156 | . . . . 5 ⊢ (𝑎 = ((√‘2)↑𝑐(√‘2)) → (𝑎↑𝑐𝑏) = (((√‘2)↑𝑐(√‘2))↑𝑐𝑏)) | |
43 | 42 | eleq1d 2896 | . . . 4 ⊢ (𝑎 = ((√‘2)↑𝑐(√‘2)) → ((𝑎↑𝑐𝑏) ∈ ℚ ↔ (((√‘2)↑𝑐(√‘2))↑𝑐𝑏) ∈ ℚ)) |
44 | oveq2 7157 | . . . . 5 ⊢ (𝑏 = (√‘2) → (((√‘2)↑𝑐(√‘2))↑𝑐𝑏) = (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2))) | |
45 | 44 | eleq1d 2896 | . . . 4 ⊢ (𝑏 = (√‘2) → ((((√‘2)↑𝑐(√‘2))↑𝑐𝑏) ∈ ℚ ↔ (((√‘2)↑𝑐(√‘2))↑𝑐(√‘2)) ∈ ℚ)) |
46 | 43, 45 | rspc2ev 3632 | . . 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 184 | 1 ⊢ ∃𝑎 ∈ (ℝ ∖ ℚ)∃𝑏 ∈ (ℝ ∖ ℚ)(𝑎↑𝑐𝑏) ∈ ℚ |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ∨ w3o 1081 ∧ w3a 1082 = wceq 1536 ∈ wcel 2113 ∃wrex 3138 ∖ cdif 3926 class class class wbr 5059 ‘cfv 6348 (class class class)co 7149 ℂcc 10528 ℝcr 10529 0cc0 10530 · cmul 10535 ≤ cle 10669 2c2 11686 ℤcz 11975 ℚcq 12342 ℝ+crp 12383 √csqrt 14587 ↑𝑐ccxp 25137 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1969 ax-7 2014 ax-8 2115 ax-9 2123 ax-10 2144 ax-11 2160 ax-12 2176 ax-ext 2792 ax-rep 5183 ax-sep 5196 ax-nul 5203 ax-pow 5259 ax-pr 5323 ax-un 7454 ax-inf2 9097 ax-cnex 10586 ax-resscn 10587 ax-1cn 10588 ax-icn 10589 ax-addcl 10590 ax-addrcl 10591 ax-mulcl 10592 ax-mulrcl 10593 ax-mulcom 10594 ax-addass 10595 ax-mulass 10596 ax-distr 10597 ax-i2m1 10598 ax-1ne0 10599 ax-1rid 10600 ax-rnegex 10601 ax-rrecex 10602 ax-cnre 10603 ax-pre-lttri 10604 ax-pre-lttrn 10605 ax-pre-ltadd 10606 ax-pre-mulgt0 10607 ax-pre-sup 10608 ax-addf 10609 ax-mulf 10610 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1083 df-3an 1084 df-tru 1539 df-fal 1549 df-ex 1780 df-nf 1784 df-sb 2069 df-mo 2621 df-eu 2653 df-clab 2799 df-cleq 2813 df-clel 2892 df-nfc 2962 df-ne 3016 df-nel 3123 df-ral 3142 df-rex 3143 df-reu 3144 df-rmo 3145 df-rab 3146 df-v 3493 df-sbc 3769 df-csb 3877 df-dif 3932 df-un 3934 df-in 3936 df-ss 3945 df-pss 3947 df-nul 4285 df-if 4461 df-pw 4534 df-sn 4561 df-pr 4563 df-tp 4565 df-op 4567 df-uni 4832 df-int 4870 df-iun 4914 df-iin 4915 df-br 5060 df-opab 5122 df-mpt 5140 df-tr 5166 df-id 5453 df-eprel 5458 df-po 5467 df-so 5468 df-fr 5507 df-se 5508 df-we 5509 df-xp 5554 df-rel 5555 df-cnv 5556 df-co 5557 df-dm 5558 df-rn 5559 df-res 5560 df-ima 5561 df-pred 6141 df-ord 6187 df-on 6188 df-lim 6189 df-suc 6190 df-iota 6307 df-fun 6350 df-fn 6351 df-f 6352 df-f1 6353 df-fo 6354 df-f1o 6355 df-fv 6356 df-isom 6357 df-riota 7107 df-ov 7152 df-oprab 7153 df-mpo 7154 df-of 7402 df-om 7574 df-1st 7682 df-2nd 7683 df-supp 7824 df-wrecs 7940 df-recs 8001 df-rdg 8039 df-1o 8095 df-2o 8096 df-oadd 8099 df-er 8282 df-map 8401 df-pm 8402 df-ixp 8455 df-en 8503 df-dom 8504 df-sdom 8505 df-fin 8506 df-fsupp 8827 df-fi 8868 df-sup 8899 df-inf 8900 df-oi 8967 df-card 9361 df-pnf 10670 df-mnf 10671 df-xr 10672 df-ltxr 10673 df-le 10674 df-sub 10865 df-neg 10866 df-div 11291 df-nn 11632 df-2 11694 df-3 11695 df-4 11696 df-5 11697 df-6 11698 df-7 11699 df-8 11700 df-9 11701 df-n0 11892 df-z 11976 df-dec 12093 df-uz 12238 df-q 12343 df-rp 12384 df-xneg 12501 df-xadd 12502 df-xmul 12503 df-ioo 12736 df-ioc 12737 df-ico 12738 df-icc 12739 df-fz 12890 df-fzo 13031 df-fl 13159 df-mod 13235 df-seq 13367 df-exp 13427 df-fac 13631 df-bc 13660 df-hash 13688 df-shft 14421 df-cj 14453 df-re 14454 df-im 14455 df-sqrt 14589 df-abs 14590 df-limsup 14823 df-clim 14840 df-rlim 14841 df-sum 15038 df-ef 15416 df-sin 15418 df-cos 15419 df-pi 15421 df-struct 16480 df-ndx 16481 df-slot 16482 df-base 16484 df-sets 16485 df-ress 16486 df-plusg 16573 df-mulr 16574 df-starv 16575 df-sca 16576 df-vsca 16577 df-ip 16578 df-tset 16579 df-ple 16580 df-ds 16582 df-unif 16583 df-hom 16584 df-cco 16585 df-rest 16691 df-topn 16692 df-0g 16710 df-gsum 16711 df-topgen 16712 df-pt 16713 df-prds 16716 df-xrs 16770 df-qtop 16775 df-imas 16776 df-xps 16778 df-mre 16852 df-mrc 16853 df-acs 16855 df-mgm 17847 df-sgrp 17896 df-mnd 17907 df-submnd 17952 df-mulg 18220 df-cntz 18442 df-cmn 18903 df-psmet 20532 df-xmet 20533 df-met 20534 df-bl 20535 df-mopn 20536 df-fbas 20537 df-fg 20538 df-cnfld 20541 df-top 21497 df-topon 21514 df-topsp 21536 df-bases 21549 df-cld 21622 df-ntr 21623 df-cls 21624 df-nei 21701 df-lp 21739 df-perf 21740 df-cn 21830 df-cnp 21831 df-haus 21918 df-tx 22165 df-hmeo 22358 df-fil 22449 df-fm 22541 df-flim 22542 df-flf 22543 df-xms 22925 df-ms 22926 df-tms 22927 df-cncf 23481 df-limc 24461 df-dv 24462 df-log 25138 df-cxp 25139 |
This theorem is referenced by: (None) |
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