i.dragon/lecture notes/groups-ch1-2.pdf · 2015-02-15 · sub ctsoups , {tjet spa ces anro quotteik...

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Uroup -Theory - Trnrlz gr6u-ps, classia( l-,te Groups and 'Therr R"p resen{a.fiorrs I I By Chtn-hn7,tlhrg r.are I. Basrc funf fr*ry il. 6qhis fl*ry "f dynomia,l quafibns IL. Baatc RePresenlahzn h*y ry. ftepresentah'on s of SU(e) a,nd 51.F) e*c T Semi-srrnple h'e AQebms W Furfher Applicahon s

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Page 1: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

Uroup -Theory

-Trnrlz gr6u-ps, classia( l-,te Groupsand 'Therr R"p resen{a.fiorrs I

I

By Chtn-hn7,tlhrg

r.areI. Basrc funf fr*ryil. 6qhis fl*ry "f dynomia,l quafibns

IL. Baatc RePresenlahzn h*yry. ftepresentah'on s of SU(e) a,nd 51.F) e*c

T Semi-srrnple h'e AQebms

W Furfher Applicahon s

Page 2: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

r

I

I CI-tAPTER oNE : GRoUP THEoRY

DFFNITI oN : A 61,*-.p CT ts 0\ set- e1,^iPP"d

^lr'-lh 4. " P- l*tcx " S|yrrt'dtlL"Q- Sr,'ch tha{-

(t I (r--1\.7: x-'(J-z) V N,1,2(q(z) lee$ st I-e--L--eJ- VXeQ

e) V xf q e't-l rr st dl-r- Q-= T(L

the no*;crnn "f {rcru-p usuathl 6ca,LreS ds

@clryrs. th ge-.r&ry rdY5y rn mztvtes . rh ?fuls tc SrrExq^pl.e- ' Linear. {tamsfisvnnqf,ttvls on 1(] , C,t

lhl rn a,.tr[ €ro"tf s

Mr,(R) :

p Vo d,.a cf,,.t t hxn [reat wraln'&€s

r-+

[.r(: i&/^ri{-l r,nafriX - t:

..:,

faur: A € M"(tR.) is i-nvertibtx

GLn (R.) :- f fl e M" (tR) I JLf A+ o 1

st-n [lR) : f AeMn (R) I UtA: I ]O(n):O.(R): lAe Mn(K.) tAtASO (n)= 50. (tR) - SLn (lR) n Ofh )U(n)- f A € M^[A ) I Ata:fn t5U(h): sL,,(a)nu(Y1 ); SpCn)

1

;'Jl fi5l8J

u'? t^(+z'Yl+''7 l'{tlr8J

l:It"IJ

(+ ditA + t)

o ,=\..1' a\.. . .

^ lA ,-,__,a :l

t' rt t u

- fL'5 +

L l.s+

/\

I:'1 \ "r

-Tn J

, Loonlz Ary.

Page 3: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

EXar"lle , Purrt^taf?cnn 6r*p + 4 f;-,.,,t< set-S,4"trneta'c artrrlp S "

a ftnife 1rry1 De c,o \os''fion

Tnrns Po* ifion !

(ii ).- swilch tSn is Eenerv'teA

3

413)

wr*haa

: ( t 3 ,8 >.(z( ),i H.)? )..- . -: (ts58).P6

and 1 , al,l o*reYs qY€ &'red

bg l+an Po

srlilns , eg .

n\unt)

l: rL {sh ,s"is

c(tc

/ f, L.,3 +..5 ( 7.8 \( i'-'(" s-"4 t z ,t f, l

(i, iz tt ir)=( i, ir)'Urfr-r )'-(itr'g )(?r t, )

PAR.I TY ;= a/en cN odd vra {f of fransposrl'rorns

Alterna*iry {c1tP An r= I'r e Sn lnr iseven }

fAc,'r, Sn is genevt^ted b'l

(tz), cl3)r cttL )

An fs flonev:atted bq 3 u4c;tzS (i jk )

F{c z Ltrcm1 finite qr-g is a sc^b3rcLrp of SN

Pf , Let tGl- N, {hen 6 < Jru viq

Ary ge G ac-ls an" lhe sef G 't viQ gchl: X'h

is ^ Permufo,hbn srut& TCh)=Jhz )J hr=hz

RElvlA e K : S^ is not abeJran f."' h v 3

tr is cp,tled abelran if flh - hq Y 0 ,h e q

Page 4: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

FxornpLt , Cy.Jic tt6rys , Dihcdrql 3Yoe,PS

Cyclic XYW C.n "

, ftnitz Su,bT"W

0 "r^ eVo,fed, l.V

Kryn = l*s+[''+

+ so(z)

numbers

modn t

, CA ,n7le'X

. infegers

. Ab#+tcr gYW

tr: (t- I *n: e

pihe.d ra-l 6rc"f Dn

. qcO(z) ye/n-bY

- Snt

Kz(n avd t7

,F.\

Ai\-

Lff t'eh

I

''r1f-aa

-lr t'

a'n 1hlI

zlt If

hJ

?kih

/rZ

CsS

ez

aa

ztt ie-T

1

reflechon

uota*ioutS

r+ fledrotts

d,I

--til

.l

Syt"melries of a necklace

Absfuoqr 1Yryq:(x,Ilt:l ,lLl

IL"t -L'-n-l > *',/ '

Dn I= 2fr,, non - al>elian 1W ' ,

if nv 3C" as *bgroq of Sn

Cn: <Dn 0s subgr6&P o { J^

Dn= ( (r23 n

)>

t

\

),1 r u )(z n-z)- )

Page 5: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK

l-e+ H< tr be ^ sub growP

a (,teft)corer { H is a subsef of +he foym g H

tAcT: IrHn g"H+O €+ JlfueH e0t H : J=l-l

ff 3,H A 3.H + I rhen Stht :Jzhzso 3l 3t - h,hlt €H, Bul- then

fw Sotne hyhz

9/0tH:H + &H:1.HCoroltary z A unique decrrnPosihbm of G

&- H U a-fl u bH t) '-*' v s(-t

l-et CIH &.nore the ^sef spaca l gt+ I ;e=then fq/Hl-: f.tiH7:: [tt/tlL '1u,.!e.y<

A co.Sef aH is NOT ^ qY6W unless a, eH

FAct I JH 3-t is q subgrDnP of q , called.r c,sn.ju €qfc {rou,}, op H

. (gft,3{ ) '( 5h.|-l ) : 3 hrhrll ( 3H 3-l

. (3h g-' )-l : (9-l)-l h{ 3-t : 3 h-' 3-(Ln arder W elA has q, in&'rced $ro*P slntctur{

we Fred 1-1.'r^l 3H X-t : H V 3e 6sach H is cat(ed rErnal sc^ b3roup of G : fi < +lVe wqnf [oH ].t bH I : t ab H 1ie, qh,'b;hz € qbH<+ Ahr b e abH (+ hrbe bH(+ b-rhrbeH<+ b-'H b cf-{Any subgro.rp of an abelian groap is norno,l

Page 6: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

! , ' ',-,I ' rr

If H4fr, +/U ;s +he luoftent groap

has the na#t,l'lo.l re{.uction ncxp G + G/Aay g H 3=- AH e e/n eg T+ Z/nZ6ROup HoMoMoRPFtISM :

A rn4"p <l : G -> q' is a !g-1i1" rnoY fu;t_ry

if Q(a.b):cp(q).?(b) V a,btG. ?(e). e':.pte):?[qq-t ): T(n).?(^-t)

+ t(^-()- t(a)-lTYnqle 3rou1 Tn V <gsr.rrel lablyowp Ker.P< q - f TG t q(1 )= e'y

. Ke r ! iS a r''torvrnal SabS "o

Uf s lrr Ul

cp(sh3-r ): q(5te(l')?(1)-l if y([)=el:.?(q)e[9{): {

ie. J KerV 3-t c ket Y i

THE KOl"r0RPhLM THE0KEM1 :

q , e/ KeY! e Inc(

Exanple: H<q,lG,Hl:2 + F{<Ge1 . Cn <

?f ,LetJ4H *hen G-HrrXHalso G:H UHJ

+ 3H:Hg t€. 3Hn-t :HlNarnning z In Aereval , teft cnsefs qre quit".&iFf erent tuitlt n\hf 64.r€f.g

Page 7: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

!.

:

' ExMPLES oF NoRl4AL suBqRouPs:

, . FMif< qbelian gYo(^p is eas!

, *s V/f,''L x Z/f!'n x x Z/p,"7-,.

I H ere 1rt d-ucf SronP (71t Crz is d*ftned Ay

' (3tt8z)-(ht,h.)- (Ttht,Lth=)

o tf 11 < 6 , then q sAoald be some kind 6tJ

, +1nti sted prodtc'r of e/n ad H

' Lente,, of & , T(tr), z(t): t hetl h3:0h v xtftT; /,(a ) is horYn^l 3%b) 31it fnnyvlu+r^+rrv 1Yry of (r z LG,fr ] - ( /

t G,br7 is ++/te suL1wuP of 6 {enem+ed Vy a[f' L{.m,/,4vtt"ils - lrh:J,- ghn-lh-l '.1\.,.. ,,,,1

.

_/ , ,f, is noYrna.l sruLe r( L1 ,hJ x-t : [x]a-t , { ,l d{]

, FACT : q' ( s Iile Srna((e5f hovmal s,, b0 roaP K' oF Cr sucl'r '++ut G/ K is abe{iar1it, A[el;an) TE 3 t 6-' € A + ghTl h4 (. Ki

; We will see la{',er fl'taf iF G is a. p A!'o,rP', +ho:r is , I Gl : Yn fu ^ Prm4e P ' +Iten;i Trl,6) + f,nt

Page 8: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

&RCtjPS Knruer oN A seT

&f t be a Fnite Arory oei"g on a

For reX, slab(il:f Setlg*:/Orbit(r-): Ox c X

-fhere is an L b 1- c^rfespon4enz :

frurte sef xTcG

ICons.q\enCes :

Class Fwmula :

Sum oveforbrB

lxl:zl.

fIal

I+,. t-\-la

ta

.aao, t t

, i',

" 1

i,\,a

\

l-*{ 4 rt-in t<,JJ-'Z: X: eLr U...UAX61

Ltnion of&isiornforbits

&zNonce that st-"b(3x ) : 3 slz.b(x) 3-tApp( ic-atton , Any fi-nife gyo&p q wifliordet' ?' , ? A. BrlrnQ. , nnust be qlpcf,ien

Pf' L*ffac*son X=& by J$)-AX7-tthen tq l: lz@)l+7ru'StabNl!Zbll:l ) P' - l+kPIZb)l:p + ln+ Zb)--(I ), h4 Zk)fhen q = t hi Si l o<i,i s Pl abelian +-

6f stabtr) * orbitH) - Gr"

Page 9: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

It. Buvnsidek F,srmulo. :

h umLer of ovb;*s {V - latFrx(1)- lxeY llr:x-ICnnsider qh orbtl Y, ry Toint x t O isc4wntd lstabkt! +irna rh >JeGIFix?) (,Jo f0u i,ohok a*ai+ is c"cunled

r q' stabcx)l' t t{ab 6xt I -l & I +- nes

A pplrco*i on : flo* man\/ dwtrnc* n\(h c*lwed

iable clalhs aye there if here are I c,olavg

avotial.le ?

_ : [T-=--J a:

#.',21::TrL#:^ul1Ii -i r^lith angk- 10" - Rtl

: , i------'l

X: Att 1n' doYed loble-

--: . , , .*'. clo4hes

t ,t , \ dts tnct on€s : NIthe CaSe tt= 6 )

N - t, (l Fix @l+ lftx(R)l+ lFrx(s'1f * l6xtr:;1)

_ + ( Ln.+ L(+)'* L+ + {+). )+ \ 'J' .n

Tn generol , if n rs even

N/: +(.Lh'nLLt#t + ,Hl )

s1A#tFrx n )[

Page 10: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

Sylanry3 TeoYews

I l3l t&l= n = ?" ^ w,*h ?tyn , Hren

+ H <A with tFt I : fe'. inTl',,.i i .s,,,1-,'\v-nr,.i-

it. Anv p subgybu? of G (s crn.{irrneC fT^ q.

Sylenv p sqbgy-otr"p

IIL Ary tWo Sylar,rr p 6rD,,r,?S qy€ c.stiulcteIf,.Let- S be lhe hLrrnberof Sy(aru ?-|roufS

4herr Sl n4 a,nd S=l (rncd f )p.oof:r l-t X:lScG ltsl:Per, fhen

rrz r_ r?ern ?e ru (pem; ) (yem -pe+ t)[A l- L oe. :'r- Pe {

:. m . Uen-t) -- Qem-re +i ) - rso ?+ lx l

llt U acfs on X by left vnutbrpl ica*ionsTtte ./ass firmu{a

lxl -> (+ e 5; sf. ?e I stua(s,- ) I ?, m

But Slf?^bfE)+G (rnless rt:.t )Now USe fn&ucfi or1

GrcluU (a"eY\ : ?llal + t 1e +P

o{ arde r prl

a

Sroupr<e

LetPi&Le+

[Cl=|em , ?t,rn, H ^ Sylaru

h€H, h#[ rhen oud(h)-?r,j : l,',Pr-r fhen aYd (1 ) : p

Page 11: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

THE TFc+ilvtq0E oF GRoup Acrt oN oN 5ETS

Af.Jo SY?4W3 THeoKeMS ARE 6nS(C T00LSTO STUDY -n-r E JTRUCTUKES 0F HtllT€ 6Rouf 5

DEflrur?oN : Cr is "*s rnyl<.tf G hqs h o hlntrivtalnovww( sqb6rorrpS

o lbl: P t , ? ,"( ?rimes g G ts nof Srrzr yl<Lel F< X

H,rH=, ---,Hs Syfaw 1 sc^tobrcu-?s

slP , sEl ft) + $:l anless

S o l-h e Sytnru 1 lroq ft <o lf 16l-lS,llten G !C, stCsxCs

15=35, 3<5H - lhe Syfnv 6- St,T,^1" <&*r -tls , S= ( Cw,d E) + !: ( , so

K = fhe Sylaw 3 Xrory <clea['1 th^f

H r\ K : Ie ]H'K:q

) q * H"K s C5KCr

We ( iSt $6fhe m6Ye otPP[ ica.tton S

. Ie !: P'L , f ,L prines J G is nof strnFl€.

. fj',e ov,[y srrnTle groups G wifh le I < do

a,re Cf wtth ? prinn€ <We Wi ll see lqfer lhqf A 5 rs srr'Y4 ?leNoh'ce lhat tAtl : 6o :

. All fi'n,{e sirnd;6roupS ^ye cla,ssifi?d !!

Page 12: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

CHAPTER TWO : GA{AIS THEOKY

SOLV r/Vfr ftt-YlrtOt rt tAL EQU NlOf\8 8Y'f-x'z+ Lx+ c. - Q ( B"bYlonuns B'c ? )

X'+ z lx +(+)':(+)"-c(* " *)':

t'J'4

Atsume know how +o sblve Tt: LLA<fhen Knaut hout +o solve X24X + L : o

X3 + LX'+oX -+ d - e (teno, Cardano tst+o)

re4bcs X by K-+ r Jor

x3+ px+1- - o

kt (=(L+V) 1Of

ut3+V3+ _s:4v (,(4!u)J I (!!_u ) + 1- : o

F** TUV+ P:Q , ic. 1,= -*uts + (-* )'* ?: o

+ il6+ gq3- -,?s l,'

,1 -?= " '

ur3:+tlWLor or,-t r p:tSol uli6 ns i

X- oof i r/d+fw'i ^N'*f^ahere u)3:l,w*1.

Page 13: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

: How ab&Lt X4+ f K"+ Lx + Y : o;

' lef, _. (x'+rLK+A) (x"-LK+f.:, x+ + (x_c,,+fl x.*(tl_ad * + Yi

,5 l-o'**:f : J ),'-(a+p),x+v:o/ ( At-

I f -Aa -- 3. I ,\'+ lx -r:o', flard +o pyo ceed But ELr'/ I ca,n be slved I.

,Kctffi, i, 4!&1, kdais, ̂ ,t,, genero-l poly h o rnt a( e1c,ta+ion s-ttis ' ,!fn;a/$i'ff Ca^ not be sotued bq rqarco(sl\,rl

Ga'utt dtd show the ( lSoo ? )

FutrMMeN/TAL THE0(EM oF ALkEts&A.

Evenl f 6l € Ctxl has a, ruor fn C

Tle^ of Pf ' 6er 6 -nP rolates n l+nes :

C+ S'- f ze Cl tzl:llz -fE)

l'fztt

J (tl : Z"+ ont Z'{-u'-'

: Z^(t+o(Zl) n Zn: rneine

? (Frva*r \I tsas ]

)

h frmeSo@Ll'h =>o

Page 14: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

64146 GROUP OF AT\i EQUAIIO\I

' Luf f(x) € Qtxl be rwed'ctubb' nonic

ftx): (x-o, ) --- (x-otn ),,:i€C,No rnutAyb ytots srue (f ,f ' ) : /

l:.f K : Q.(o,, ---,4n ) c C, be the

number Sqstern ( - fi-e(d ) Aeneratei, bg antl

t-z*r'anal e4 pre ssionS rh ol.r , - _., o( n .

talois growl 6f : e(K/A ),= AutO( K )

A*^(K) : f ?. Kg K st gla.: rJar*l cf pyes*v<s (+, . ) l

fACr : G c Sh ds Tevrnutv-ticvt Aror4,of 4t,---i otn

?f, I-e+ f,"): Lh+ah-iLn<+"-+40 , ^ieQ+4,en ? ft"l -- f tx )

/ o(X-ar).-rK-otn)( x- ?(4,) ) ... (x -Wa,l)u n i q^eness of {oc+on;u*ion

FACT z !( iS a frnite d,imertsiarto'( VecJor sFAover A o,nd lAl : dfnqK :: t K'e,7A I I disc-ttss ions 6(e valid * lr"n a is rephced tot'1

4,< t ^ ftnile e'*temsian of Q. .

Page 15: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

Met-tnd : fr,'ttt,{ voofs one by onl

' f[x) : X3 -z e Q,lx ]Ftar'nplg

K:Q.('Jt, tJT rrl ,

tilT .^l")ll

Spt;+rng trztd of A. (tnlT, ar)

x+lrx*3G*/ r \ tl.-l'':"l"lt,;l

ovel- Q..({tr ) A(t^1" )

)\

NrJ- 4, sp{i+rinJ fr.erd

a(t^Jt) - Q<3Jr, ',{T,is a 3-dtrrnenslonalAkd lAut (qPJr)) |

Q (t^t ) - ar( t^l , .*<, I >

Q(ut)

/r/0_'/ \

Sp(r+no3 Rztd ol fr:./(or Xrrx+l _o )oVey. e

1> * acx:/(x:_z)rcctor spo t.e oVCt^ E: 3 - d"J (xs_Z )

Q.txi/(x'+x*r )is z-d;mensional /q , lAur^.(a(r)) l- / : ["3(x+x+r)

-fhere is an L +o 1- c'srveS Pond-oArtQ ,

FUNDAMENIAL- ftEQRE 4 oF &4106 THE6Ry

KfCIK,,' n \"i'

' *' "') 4.i\ .

F' # c&/il /H, k': ihvaria,nr^.. '.. / t ,,' ;ub freld

I . ,i ,, ,/ , p,'e. t---+ '''Clo(K/a,) a_

F/A, s1, fiafrng F;etd € tl<t and a{F/q)= G/H

Page 16: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

SOLVABILITY

W ftx) e Q txl , Slo^1- 10 solve rhe rcrots aX

mdicals , m&y frrst repfau- A. bq a,

u1 olnfornic axfens ian k - e ((v ) c^,her€

fu is tl,to N-+h l-rrcfs 6( i* . (J _ |

?rcX fV lar!(, and d;vistL(x ennrgh

FACT z The radaca.l wtasron X, A. - ois SPI i+rin3 aznd +l^e halois E.*p &is 4dic ";,ith lelln

\ ftdo;s' *he-orerm

i

nrfi,

\ abelian

FAc:r: &(q((n,ye) = ful ra)* is an

abelnan {vourP , Th &.cr, is a. d'irec,t surn

of u1cltc € Yt I^/Ps

6qmoJ sub 5

6; /6r*, rB

aqclic

+he "3;1^^e+vt/ breakin j -

the- - prrtr de S

Ie

j

ez,tr''.q

,A{:

6r,

AG

f(f"(I,.7{e-

l

)

)\[7,

qclolorn;

Th" abwe d'aXraw' is

&, ajrarn , rtols 6Ye

Page 17: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

D"fr"i*,on t A firri€ BV"y q A solvabl<

if J q selu?uce of subgvoc'r+s tt, 0^, "'5t. G>&tpG= vfelq,nd G;/ G;*, r's an abe(ran € ro*P( elwiValent tu recluare +huf 4,/Gr*, a,tclrc )

ThL6RLt\4 ( Gn( ois )A prqnorn;o,.! r\ solveble bq ,zrd^'cols fF andody if ifs G*tois 7t-tup R Salvable.

Tosk :

L Shaw +h*f gener^( pdyhomiq.l E,*rionSof drjr€ e v 5 /'s nof solvab le

tr . 6rven a. P "l^1n orv't ia' l, hcu^.1 to ul cn tqle

,'+S Galots A,roup 1.

Remarlqs 6n [oter &evelaynon(- t

. GaloiS' rJea 6n Le used +o Jeal wrth thc.

oxplru't solvabi t;1 pvobtern tn oDE ,

#ntLegcl.l .rePlaad by Lfe Jrry, . If we altw some -slM of lheta funu'org,

then qny po\^6rnial Can be erpltctt\ solvd

( Senne+n1 4 a"Le l;a,n vari'Qties )

Page 18: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

THeOREM . An fs s ih4P(e. ,f nv 5

Pf, w Anv l(+ le3

if K c't nfains a 3

K us il I uonla'in a'U

CLaim :

tf nof

ulcll* , Socl Ct23),Wn3 aryJ-os

] ut '\ ltz )+s " \-l

k e.^ )(rz3) (; ik t*, ):(^.ik)vn.r4^1 aS$uvvt-9.k bq A)LAA , otdturtllig! U/24

(Q-w, ) T

srncp A r, tr /,enert'+ed bg 7 ndt- ' ,

a.ri( t rmPlY tK=

An., so An is sr'7Q '

Lot l+ * e K has Intuxi ma.I nuvrtb{-r^of

frYed po ints , then cl' t's a 3 - cAytLL

lhen q Jooks [ke 'z

ll2l[t 1

/7'x

Bw+

++:n'S

A.fr: I (23 - - ) and rnoves soY , u, t<,Drr-q. qx. +. ' r! t- -. ',i. ). tltll I {} -j-

-JrLe/r

P e- (3 uF) , 3111 p ot pi , +r,en

A ocl - (rzU---)--. K6/&.41 <(tz)Wil , havQ ot1 *otW ot2: o(r (-l + I (: fof -l d.-{ )V i>.6, xf't)=i + olz(i )= i

Case A. dzE)=2, but d ynNes I | 2t 3, +, 5 -?ts-

&sp O . ob-il):(, ob(z) =2, Lul o( rnayaas (, z, 3, *

Page 19: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

Covol lory , S^ is nor solvable i f n 7 5

S, DAn>RernavQ, S=rSr, S+ aR So(vab(4

Sz ! Cz nof interes+i ng

Sg >As 3Cs u1dic,oK.S+ >_M >!=v fe I

,l\/.

cv4ev- ! z. or,Je,v' $-

K .- I C, D,:'4) , (t/L)Q3), ct3 ) (zl+)] e Tt0.a K(e,^'rls 4 Ar",-p

is 6 no.rral sub A*f "f A+: Ih fact

eu/K Y 53 solvable

THEOR fJtl ( gu fsin i - Abe! - Qalo is ) B zo "''The elua*ion X

n- o1 X'-{ + Qz X'-' + 0)" an: o

for n > 5 cnn not be solvcd by rad-icals

over Q (ar r"'t &n ) .

Pf , tf :'l:::;l:,r:., ;::':" o'

then 0,i = Srl^ne+u'c P"qnomi^l in tt/'- i tn,( deyen i

So itu 6afois Ar% 6f +he s7k+ing fizH

Q.fttr--)tn) o{eY A-(qtt"-t4n ) is Sn .

Page 20: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

-f" fi n ish the sfury' of Qal ois theovy , M€

should of leasC {iv€ ah c,oh cret< examyl<

us h ich iS n o t Sol uab te by ra&t Ca[ s

THEoREI\A' Le'f J$) e Q.txl be an twed.uctt'lz

polyVtornia,l whvll haS eYactly L h6n-real roots

in G , 6nd dq f - P is o- Prrme nunber v 5rhen t*te (76,t ais Aro o'p is Sp flence f txl - occrn h6t be sdved by rz,da ca.ls .

Eyftr4PLE , flx): X5-t 6X + Z

The g^fh of f(x) is :

has aXaot\ 3 v'€af roo'lS

f (x) rb ir(e U^lblz ft (lows

frr- Eiseznsleinb critevion- -

FACT, Lel- P be & Prine, Ga tftf Q,z) and (t rzr "- rf ) e ? , !*^,1 :ff.S of IIre *Leol'ezr: !' ' I i

Let- f(x)= (x-'tr ) '--( x-"1 ) *i e C

srhg- lEc"tt)' Q. l = bSf - 7

so tot:tqtxt, rur)'q. I: ta.(ur,, ',df ), qt'tr ) J' t q(nr)'( J

so Pl fql , sylil .? + !.t i..9 *d:',t 7

Tfu hot o. rj A frxes o,(l real r'otjts

and wd',an1& +h-a Z cf)< r60ts

e 3-rceCTcSp st t lsokslike (t,z)- END

Page 21: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

H0\ / TO DETERMINE- rHE sdvABl Lfff 0F A6lvEN pNlrL 6RoUp EFFEcflVELy 7

Ke cd.( I the dryl'val fl rc,rP (.f-

+{.-a Syna( lesl v\avya6,( Su b6roaplcr,ql is

K st.e/t< is a,be(ian

Let Q" - f.(,4'7 , q [t) : lG", q" ] etc

DeriVed noyrnoJ sen eS

&- q" > C+t v &tzl V Gl') v v G'k) v

?r, €:

+.

THEoREM : (a is Jolval'le tr; q(l') - te 5 sorne k.

6-ck) : f e} then E ts s;vable.

Str,rco CT'd'/O[d+r) fs q'belian

Lsf &:Go VGrvGzV--'v Gt:Sutch tha{- C, I G;*r is qbelan

abelian + Gl =Ct'a.belran >abeli-an + G3 >

+ q>n

fel

GlG,

8'/e,fu/qu

Exa.rnpf*: lCrt:t,n,

+

?(, i-tod seeh *hatJ,

c.l Zt k) ,: o(so

+ Cr is 56lrra.ble.

' Zr(*)t ,i' v'' o "t

+,-' "ia.

I

^ ?- aro,^fBy rr, &,r ctioh eln (erl

o/z[a) v G, /zb) v+ GvGtv vC4r-

is so(va.ble

v G,lzrur\:fe%t,G) ab

"l ian

Iel

Page 22: I.dragon/Lecture Notes/groups-ch1-2.pdf · 2015-02-15 · SUB CTSOUPS , {TJET SPA CES ANrO QUOTTEIK l-e+ H< tr be ^ sub growP a (,teft)corer { H is a subsef of +he foym g H tAcT:

REFEKEN/CES

Eastc Groug ft^ry and Gqtois ft^ry. lr4. Arti'n : fit-GEBRA. N/ . Jac,"b soh : B ASIC ALCTEBRA Tk"?=sen1o.(+on **ry' T P- Sewe : L/A/EAR REpREJeA/rArtoNs

oF FfNflTe CrR0uPS

. T Brarker / 7. Dieck : R E]XESflvTAT1 ON_Sof cAMpAq UE 6RoupS

Avouy Theovy r-.^ ?hysrcso B. L. vander waerde.n : GRoup THEaKy

AND QuANTUtt4 MECI1A NtcS

. S sfernkrg : eRoT,nAA/D pHystcs

,t,^\