fldextrspundglemul - Mathbox for Thierry Arnoux

	Mathbox for Thierry Arnoux		< Previous Next > Nearby theorems
Mirrors > Home > MPE Home > Th. List > Mathboxes > fldextrspundglemul		Structured version Visualization version GIF version

Theorem fldextrspundglemul 33699

Description: Given two field extensions 𝐼 / 𝐾 and 𝐽 / 𝐾 of the same field 𝐾, 𝐽 / 𝐾 being finite, and the composiste field 𝐸 = 𝐼𝐽, the degree of the extension of the composite field 𝐸 / 𝐾 is at most the product of the field extension degrees of 𝐼 / 𝐾 and 𝐽 / 𝐾. (Contributed by Thierry Arnoux, 19-Oct-2025.)

**Hypotheses**
Ref	Expression
fldextrspun.k	⊢ 𝐾 = (𝐿 ↾_s 𝐹)
fldextrspun.i	⊢ 𝐼 = (𝐿 ↾_s 𝐺)
fldextrspun.j	⊢ 𝐽 = (𝐿 ↾_s 𝐻)
fldextrspun.2	⊢ (𝜑 → 𝐿 ∈ Field)
fldextrspun.3	⊢ (𝜑 → 𝐹 ∈ (SubDRing‘𝐼))
fldextrspun.4	⊢ (𝜑 → 𝐹 ∈ (SubDRing‘𝐽))
fldextrspun.5	⊢ (𝜑 → 𝐺 ∈ (SubDRing‘𝐿))
fldextrspun.6	⊢ (𝜑 → 𝐻 ∈ (SubDRing‘𝐿))
fldextrspundglemul.7	⊢ (𝜑 → (𝐽[:]𝐾) ∈ ℕ₀)
fldextrspundglemul.1	⊢ 𝐸 = (𝐿 ↾_s (𝐿 fldGen (𝐺 ∪ 𝐻)))

**Assertion**
Ref	Expression
fldextrspundglemul	⊢ (𝜑 → (𝐸[:]𝐾) ≤ ((𝐼[:]𝐾) ·_e (𝐽[:]𝐾)))

**Proof of Theorem fldextrspundglemul**
Step	Hyp	Ref	Expression
1		eqid 2731	. . . . 5 ⊢ (Base‘𝐿) = (Base‘𝐿)
2		fldextrspun.i	. . . . 5 ⊢ 𝐼 = (𝐿 ↾_s 𝐺)
3		fldextrspundglemul.1	. . . . 5 ⊢ 𝐸 = (𝐿 ↾_s (𝐿 fldGen (𝐺 ∪ 𝐻)))
4		fldextrspun.2	. . . . 5 ⊢ (𝜑 → 𝐿 ∈ Field)
5		fldextrspun.5	. . . . 5 ⊢ (𝜑 → 𝐺 ∈ (SubDRing‘𝐿))
6		fldextrspun.6	. . . . . 6 ⊢ (𝜑 → 𝐻 ∈ (SubDRing‘𝐿))
7	1	sdrgss 20714	. . . . . 6 ⊢ (𝐻 ∈ (SubDRing‘𝐿) → 𝐻 ⊆ (Base‘𝐿))
8	6, 7	syl 17	. . . . 5 ⊢ (𝜑 → 𝐻 ⊆ (Base‘𝐿))
9	1, 2, 3, 4, 5, 8	fldgenfldext 33688	. . . 4 ⊢ (𝜑 → 𝐸/_FldExt𝐼)
10		extdgcl 33676	. . . 4 ⊢ (𝐸/_FldExt𝐼 → (𝐸[:]𝐼) ∈ ℕ₀^*)
11		xnn0xr 12465	. . . 4 ⊢ ((𝐸[:]𝐼) ∈ ℕ₀^* → (𝐸[:]𝐼) ∈ ℝ^*)
12	9, 10, 11	3syl 18	. . 3 ⊢ (𝜑 → (𝐸[:]𝐼) ∈ ℝ^*)
13		fldextrspun.j	. . . . 5 ⊢ 𝐽 = (𝐿 ↾_s 𝐻)
14		fldextrspun.4	. . . . 5 ⊢ (𝜑 → 𝐹 ∈ (SubDRing‘𝐽))
15		fldextrspun.k	. . . . 5 ⊢ 𝐾 = (𝐿 ↾_s 𝐹)
16	13, 4, 6, 14, 15	fldsdrgfldext2 33682	. . . 4 ⊢ (𝜑 → 𝐽/_FldExt𝐾)
17		extdgcl 33676	. . . 4 ⊢ (𝐽/_FldExt𝐾 → (𝐽[:]𝐾) ∈ ℕ₀^*)
18		xnn0xr 12465	. . . 4 ⊢ ((𝐽[:]𝐾) ∈ ℕ₀^* → (𝐽[:]𝐾) ∈ ℝ^*)
19	16, 17, 18	3syl 18	. . 3 ⊢ (𝜑 → (𝐽[:]𝐾) ∈ ℝ^*)
20		fldextrspun.3	. . . . . 6 ⊢ (𝜑 → 𝐹 ∈ (SubDRing‘𝐼))
21	2, 4, 5, 20, 15	fldsdrgfldext2 33682	. . . . 5 ⊢ (𝜑 → 𝐼/_FldExt𝐾)
22		extdgcl 33676	. . . . 5 ⊢ (𝐼/_FldExt𝐾 → (𝐼[:]𝐾) ∈ ℕ₀^*)
23		xnn0xrge0 13412	. . . . 5 ⊢ ((𝐼[:]𝐾) ∈ ℕ₀^* → (𝐼[:]𝐾) ∈ (0[,]+∞))
24	21, 22, 23	3syl 18	. . . 4 ⊢ (𝜑 → (𝐼[:]𝐾) ∈ (0[,]+∞))
25		elxrge0 13363	. . . 4 ⊢ ((𝐼[:]𝐾) ∈ (0[,]+∞) ↔ ((𝐼[:]𝐾) ∈ ℝ^* ∧ 0 ≤ (𝐼[:]𝐾)))
26	24, 25	sylib 218	. . 3 ⊢ (𝜑 → ((𝐼[:]𝐾) ∈ ℝ^* ∧ 0 ≤ (𝐼[:]𝐾)))
27		fldextrspundglemul.7	. . . 4 ⊢ (𝜑 → (𝐽[:]𝐾) ∈ ℕ₀)
28	15, 2, 13, 4, 20, 14, 5, 6, 27, 3	fldextrspundgle 33698	. . 3 ⊢ (𝜑 → (𝐸[:]𝐼) ≤ (𝐽[:]𝐾))
29		xlemul1a 13193	. . 3 ⊢ ((((𝐸[:]𝐼) ∈ ℝ^* ∧ (𝐽[:]𝐾) ∈ ℝ^* ∧ ((𝐼[:]𝐾) ∈ ℝ^* ∧ 0 ≤ (𝐼[:]𝐾))) ∧ (𝐸[:]𝐼) ≤ (𝐽[:]𝐾)) → ((𝐸[:]𝐼) ·_e (𝐼[:]𝐾)) ≤ ((𝐽[:]𝐾) ·_e (𝐼[:]𝐾)))
30	12, 19, 26, 28, 29	syl31anc 1375	. 2 ⊢ (𝜑 → ((𝐸[:]𝐼) ·_e (𝐼[:]𝐾)) ≤ ((𝐽[:]𝐾) ·_e (𝐼[:]𝐾)))
31		extdgmul 33683	. . 3 ⊢ ((𝐸/_FldExt𝐼 ∧ 𝐼/_FldExt𝐾) → (𝐸[:]𝐾) = ((𝐸[:]𝐼) ·_e (𝐼[:]𝐾)))
32	9, 21, 31	syl2anc 584	. 2 ⊢ (𝜑 → (𝐸[:]𝐾) = ((𝐸[:]𝐼) ·_e (𝐼[:]𝐾)))
33		xnn0xr 12465	. . . 4 ⊢ ((𝐼[:]𝐾) ∈ ℕ₀^* → (𝐼[:]𝐾) ∈ ℝ^*)
34	21, 22, 33	3syl 18	. . 3 ⊢ (𝜑 → (𝐼[:]𝐾) ∈ ℝ^*)
35		xmulcom 13171	. . 3 ⊢ (((𝐼[:]𝐾) ∈ ℝ^* ∧ (𝐽[:]𝐾) ∈ ℝ^*) → ((𝐼[:]𝐾) ·_e (𝐽[:]𝐾)) = ((𝐽[:]𝐾) ·_e (𝐼[:]𝐾)))
36	34, 19, 35	syl2anc 584	. 2 ⊢ (𝜑 → ((𝐼[:]𝐾) ·_e (𝐽[:]𝐾)) = ((𝐽[:]𝐾) ·_e (𝐼[:]𝐾)))
37	30, 32, 36	3brtr4d 5125	1 ⊢ (𝜑 → (𝐸[:]𝐾) ≤ ((𝐼[:]𝐾) ·_e (𝐽[:]𝐾)))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ∧ wa 395 = wceq 1541 ∈ wcel 2111 ∪ cun 3895 ⊆ wss 3897 class class class wbr 5093 ‘cfv 6487 (class class class)co 7352 0cc0 11012 +∞cpnf 11149 ℝ^*cxr 11151 ≤ cle 11153 ℕ₀cn0 12387 ℕ₀^*cxnn0 12460 ·_e cxmu 13016 [,]cicc 13254 Basecbs 17126 ↾_s cress 17147 Fieldcfield 20651 SubDRingcsdrg 20707 fldGen cfldgen 33283 /_FldExtcfldext 33658 [:]cextdg 33660

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1968 ax-7 2009 ax-8 2113 ax-9 2121 ax-10 2144 ax-11 2160 ax-12 2180 ax-ext 2703 ax-rep 5219 ax-sep 5236 ax-nul 5246 ax-pow 5305 ax-pr 5372 ax-un 7674 ax-reg 9484 ax-inf2 9537 ax-ac2 10360 ax-cnex 11068 ax-resscn 11069 ax-1cn 11070 ax-icn 11071 ax-addcl 11072 ax-addrcl 11073 ax-mulcl 11074 ax-mulrcl 11075 ax-mulcom 11076 ax-addass 11077 ax-mulass 11078 ax-distr 11079 ax-i2m1 11080 ax-1ne0 11081 ax-1rid 11082 ax-rnegex 11083 ax-rrecex 11084 ax-cnre 11085 ax-pre-lttri 11086 ax-pre-lttrn 11087 ax-pre-ltadd 11088 ax-pre-mulgt0 11089 ax-pre-sup 11090 ax-addf 11091

This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1544 df-fal 1554 df-ex 1781 df-nf 1785 df-sb 2068 df-mo 2535 df-eu 2564 df-clab 2710 df-cleq 2723 df-clel 2806 df-nfc 2881 df-ne 2929 df-nel 3033 df-ral 3048 df-rex 3057 df-rmo 3346 df-reu 3347 df-rab 3396 df-v 3438 df-sbc 3737 df-csb 3846 df-dif 3900 df-un 3902 df-in 3904 df-ss 3914 df-pss 3917 df-nul 4283 df-if 4475 df-pw 4551 df-sn 4576 df-pr 4578 df-tp 4580 df-op 4582 df-uni 4859 df-int 4898 df-iun 4943 df-iin 4944 df-br 5094 df-opab 5156 df-mpt 5175 df-tr 5201 df-id 5514 df-eprel 5519 df-po 5527 df-so 5528 df-fr 5572 df-se 5573 df-we 5574 df-xp 5625 df-rel 5626 df-cnv 5627 df-co 5628 df-dm 5629 df-rn 5630 df-res 5631 df-ima 5632 df-pred 6254 df-ord 6315 df-on 6316 df-lim 6317 df-suc 6318 df-iota 6443 df-fun 6489 df-fn 6490 df-f 6491 df-f1 6492 df-fo 6493 df-f1o 6494 df-fv 6495 df-isom 6496 df-riota 7309 df-ov 7355 df-oprab 7356 df-mpo 7357 df-of 7616 df-rpss 7662 df-om 7803 df-1st 7927 df-2nd 7928 df-supp 8097 df-tpos 8162 df-frecs 8217 df-wrecs 8248 df-recs 8297 df-rdg 8335 df-1o 8391 df-2o 8392 df-oadd 8395 df-er 8628 df-map 8758 df-ixp 8828 df-en 8876 df-dom 8877 df-sdom 8878 df-fin 8879 df-fsupp 9252 df-sup 9332 df-inf 9333 df-oi 9402 df-r1 9663 df-rank 9664 df-dju 9800 df-card 9838 df-acn 9841 df-ac 10013 df-pnf 11154 df-mnf 11155 df-xr 11156 df-ltxr 11157 df-le 11158 df-sub 11352 df-neg 11353 df-div 11781 df-nn 12132 df-2 12194 df-3 12195 df-4 12196 df-5 12197 df-6 12198 df-7 12199 df-8 12200 df-9 12201 df-n0 12388 df-xnn0 12461 df-z 12475 df-dec 12595 df-uz 12739 df-rp 12897 df-xneg 13017 df-xadd 13018 df-xmul 13019 df-icc 13258 df-fz 13414 df-fzo 13561 df-seq 13915 df-exp 13975 df-hash 14244 df-word 14427 df-lsw 14476 df-concat 14484 df-s1 14510 df-substr 14555 df-pfx 14585 df-s2 14761 df-cj 15012 df-re 15013 df-im 15014 df-sqrt 15148 df-abs 15149 df-clim 15401 df-sum 15600 df-struct 17064 df-sets 17081 df-slot 17099 df-ndx 17111 df-base 17127 df-ress 17148 df-plusg 17180 df-mulr 17181 df-starv 17182 df-sca 17183 df-vsca 17184 df-ip 17185 df-tset 17186 df-ple 17187 df-ocomp 17188 df-ds 17189 df-unif 17190 df-hom 17191 df-cco 17192 df-0g 17351 df-gsum 17352 df-prds 17357 df-pws 17359 df-mre 17494 df-mrc 17495 df-mri 17496 df-acs 17497 df-proset 18206 df-drs 18207 df-poset 18225 df-ipo 18440 df-mgm 18554 df-sgrp 18633 df-mnd 18649 df-mhm 18697 df-submnd 18698 df-grp 18855 df-minusg 18856 df-sbg 18857 df-mulg 18987 df-subg 19042 df-ghm 19131 df-cntz 19235 df-cntr 19236 df-lsm 19554 df-cmn 19700 df-abl 19701 df-mgp 20065 df-rng 20077 df-ur 20106 df-ring 20159 df-cring 20160 df-oppr 20261 df-dvdsr 20281 df-unit 20282 df-invr 20312 df-dvr 20325 df-nzr 20434 df-subrng 20467 df-subrg 20491 df-rgspn 20532 df-rlreg 20615 df-domn 20616 df-idom 20617 df-drng 20652 df-field 20653 df-sdrg 20708 df-lmod 20801 df-lss 20871 df-lsp 20911 df-lmhm 20962 df-lmim 20963 df-lbs 21015 df-lvec 21043 df-sra 21113 df-rgmod 21114 df-cnfld 21298 df-zring 21390 df-dsmm 21675 df-frlm 21690 df-uvc 21726 df-lindf 21749 df-linds 21750 df-assa 21796 df-ind 32839 df-fldgen 33284 df-dim 33619 df-fldext 33661 df-extdg 33662

This theorem is referenced by: fldextrspundgdvdslem 33700 fldextrspundgdvds 33701 fldext2rspun 33702

W3C validator