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  • 7/28/2019 Thoery of Matrices Mac Duffee

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    The theory of matrices / by C.C. MacDuffee.

    MacDuffee, Cyrus Colton, 1895-

    New York : Chelsea , 1956.

    http://hdl.handle.net/2027/mdp.49015001327999

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    nt ibrary

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    .

    X ,

    A

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    E D R MA TH E MA T K

    G E N Z G B I E T

    B E N V O N D R C H R I FT E I TUN G

    L B L A TT F R MA T H E MA T K "

    N D

    irst dit ion

    UB L I S H I N G C O MPA N Y

    E W O R K

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    HE U N I T D TA T S O F A M R I C A

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    maticalabstractionunderlyingmany

    s.Thusbilinearand uadraticforms,linear

    rcomple systems),linearhomogeneoustrans-

    orfunctionsarevariousmanifestationsof

    anchesofmathematicsasnumbertheory,

    uations,continuedfractions,pro ective

    eofcerta inportionsof thissub ect. ndeed,

    propertiesofmatriceswerefirstdiscovered

    ularapplication,andnotuntilmuchlater re-

    y.

    hinthescopeof thisboo togiveacompletely

    theory,noris itintendedtoma eitan

    esub ect. thasbeenthedesireof thew riter

    rectionsinwhichthetheoryleads sothatthe

    aysee itse tent. Whilesomeattempthas

    parts ofthetheory,ingeneralthe material

    sfoundintheliterature,the topicsdiscussed

    hiche tensiveresearchhasta enplace.

    heoremsa briefandelegantproofhas

    tishopedthat mostofthesehavebeen

    andthatthe readerwillderiveasmuchplea-

    did thewriter.

    ueDr. aurens arleB ushforacrit ical

    ee.

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    dDeterminants1

    deredsets1

    rices5

    cands ew matrices5

    nts8

    0

    nors12

    antsofhigherdimension15

    utativesystems1

    ce uation17

    tion17

    uation17

    inimume uation20

    ts22

    4

    acterist icroots25

    ofunitarymatrices28

    n t eg r al M a tr i c es 2 9

    sina principalidealring29

    odularmatrices31

    s31

    sors35

    37

    4 0

    r ic e s 40

    delementarydivisors43

    ri 44

    5

    fmatrices48

    ormations50

    sina principalidealring51

    ntegralelements54

    sina field5

    aca lly closedf ie ld 0

    es 2

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    8

    tsinaf ield 9

    stic73

    le uivalence75

    and orthogonalmatrices78

    n of m at r ic e s 81

    product81

    power-matrices85

    u at io ns 8 9

    uation89

    9 4

    tion95

    ces97

    s97

    9

    ntsarefunctionsofcomple variables..101

    alsofmatrices102

    er 104

    ts104

    0

    finiteorder 10

    s108

    numerablenumberofrowsandcolums. 110

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    dDeterminants.

    neara lgebra2tofordernoveraf ie ld% is

    numbers , / , y , . . . andthreeoperations,

    t ion( )andsca larmultiplicationsuchthat

    , a a r e un i u e ly d e fi n ed n u mb e rs o f 2 1, w h er e a i s

    hat additioniscommutativeandasso-

    tionisdistributivewithrespect toaddi-

    it isassumedthat

    ( ab ) , a ) H b p) = (a b o rf ) ,

    + b

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    ndDeterminants.

    braisassociative,then

    ) e = e, (e e ) .( ' , , i, 2 , )

    mbersci)iaresub ecttothen conditions

    . = Z k C i k c , r. ( , /, f, s = l, 2n )

    eredsetofnumbers

    alarmultiplicationof suchsetsaredefinedby

    , r ) = (Z k c t r C , s ) ,

    k R k .

    eundermultiplicationinthe samemanner

    1. f thesetsR tarenotlinearly independent

    t obtainedbyborderingR tabovewitha

    e le ftw ithdri( ronec er s8), are linearly inde-

    icwiththeei undermultiplication2.

    sis definedbytheidentity

    c ) ,

    sgivearepresentationofthe algebra3.

    hesameyearthatPo incare snotew as

    ote: ThePeirces(subse uently to1858)

    alizationofH amilton stheory,andhad

    ffect thatprobablyallsystemsofalgebraical

    ssociativelawof multiplicationwouldbeeven-

    withlineartransformationsofschemata

    epresentation....That suchmustbethe

    sert,butit isverydifficulttoconceivehow

    econsiderationsof 2suggestthat

    2overgcan besodefinedthateveryalgebra

    somorphicwithoneof itspropersub-algebras5.

    lassevonMatrizen, p. 59. B erlin1901.

    undihreZ ahlentheorie , p. 35.

    . R . A c a d. c i ., P a ri s V o l . 9 9 ( 18 8 4) p p . 74 0 7 4 2.

    hm .G es . W is s. P ra gu e (1 88 7) p p. 1 6 1 8 . t ud y, . :

    V o l . 4 (1 9 04 ) 1 0 .

    . M a th . V o l . ( 1 88 4 ) pp . 2 70 2 8 .

    erneA lgebraV o l. p. 37. B erlin1930.

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    dDeterminants.

    hetotalmatric algebra9ftofordern2 over

    ets ofn2numbereachofthe type

    operationsandpostulates:

    dB = (brs) aree ualifandonly ifar,= brs

    sdefinedby

    + b ) .

    nabeliangroup withrespecttoaddition,

    hee lementsof thering9 . The identity set,

    will bedenotedby0.

    tionisdefinedby

    mn multiplicationof thesets. Theproduct

    O A = A O = 0 f o r e v er y A .

    ociative,sincemultiplicationinfitis as-

    Z u ( ^ ) ^

    A ( B C ) .

    vewithrespect toaddition,forthe

    ( a H + i ) cu )

    A C + B C .

    B ) = C A + C B .

    tricalgebraoforder n2overaring 9 is

    sconnectionbyspecializing9 , formulti-

    allynon-commutativeevenwhen9 isacom-

    erseastomultiplicationofA = | = 0doesnot

    ingw ithoutdiv isorsofzero . f , how ever,

    ite lement1, thenthematri = (

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    dDeterminants.

    d co lumns, B nhas7row sand co lumns,

    sand co lumns. t isreadilyverifiedthat

    r iB i s ,( r, s, = 1 , 2)

    c s / 1 < ; . , Z ? i . a r e mu l ti p li e d r o w by c o lu m n .

    onsofthematricesintobloc s,providedthe

    dinthesamew aysastheco lumnsofA .

    ray tomeananorderedsetof e lements

    e ua lif andonly ifeachconsistsof thesame

    correspondinge lementsaree ua l. f

    be arrangedintheformof arectangle.Under

    sumorproduct oftwoarraysmayhave

    ntheyarematricesor asinthelast paragraph

    tfrommatrices,but nosuchoperationsare

    array.

    ceofanarrayof 2elements, butit ismuch

    emberofa totalmatricalgebraforwhich

    andmultiplicationaredefined.Theimportance

    sfromthe rulesofcombinationofmatrices,

    ayberepresentedbys uarearraysisin-

    ly remar ed: Oneof thef irsto f suche -

    relyuncalledfor,especiallyin ngland,

    w ordmatri )ta etheplacea lreadysatisfactorily

    .H owsatisfactorythiswaswillbe readily

    h te t b oo s o f d et e rm i na n ts l i e c o tt s 1 . A

    dcertainlyaddfurthertohis creditifin

    hemademanifestbypreceptande amplean

    ngineachother scompanythetermsarray,

    edona consistentterminology.Theword

    sedby y lvester3todenotearectangulararray

    canbeformed.Theconceptof amatri as

    risduein essencetoH amiltonbutmoredirectly

    amongothers, uses matri " f o rarectangular

    oramemberofamatrica lgebra5. B utthees-

    hateletagrees,istodifferentiatetheconcepts.

    atiseonthetheoryofdeterminants. C ambridge1880.

    o y . o c . . A f r ic a V o l . 1 8 I ( 1 92 9 ) pp . 2 19 - 22 7 .

    . V o l . 37 ( 1 85 0 ) pp . 3 3 3 7 0 - C o l l. W o r s V o l .

    ndonPhil. oc. V o l. 148(1858)pp. 17-37-C o ll. Wor s

    .

    upesabeliensf inis. Paris1924.

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    dDeterminants.

    atrices. A matri o f thetype

    ]

    edefinitionsof additionandmultiplication

    + i h, h, . .. , ] = f t + h, 2 + l 2, .. ., n + l n ,

    1, l2 ,. . ., l ] = ft l1 , 2 l2 ,. . . n ln .

    o fw hosediagona le lementsaree ua lisca lled

    , , ... , ] , th en k + l = k + i , k S { = k l ,

    atricesofconstitutea subringofW iso-

    f or * a nd A f or k A . f 9 1 is a r in g wi th

    / .

    sacommutativeringwithunit element,andif

    e ry X i n W l , t he n A i s s c a la r .

    s

    , thereresults

    ? drpdi, la i,, a rp8, = drpats. (r, s, p, = 1, 2, . .. , n)

    p t h i s gi v es a r p = 0 , wh i le f o r = s a n d r = p

    s s.

    cands ew matrices. Thematri A T= ( sr)

    ,)bychangingrowstocolumnsis calledthe

    matri suchthat T= isca lledsymmetric,

    T = Q i s c a l l ed s e w 3 (s e w -s y mm e tr i c, o r

    M a th . V o l . ( 1 88 4 ) pp . 2 70 - 28 - C o l l . W o r s

    4.

    differentnotationsforthetransposehavebeenused,

    , A 1 , , A . T h e pr e se n t no t at i on i s i n e e pi n g wi t h a sy s te m at i c

    mayfind favor.

    e w. M at h . V o l . 32 ( 1 84 ) p p . 11 9 1 2 3 - C o l l. W o r s

    3 3 . a g ue r re : . c o le p o ly t ec h n. V o l . 2 5 (1 8 7 ) p p. 2 1 5 to

    vr es V o l . p p. 2 28 -2 33 .

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    dDeterminants.

    K ) T= A T + B T + r T.

    sacommutativering(A B ... )T= T...B TA T.

    i ) T = C Z & i r , i ) = B T A T . T he g e ne r al t h eo r em

    ringinwhich2 = a issolvableforeverya,

    er91is-uni ue lye pressibleasasumofasymmetric

    , T = , Q T = -0 .

    T= -Q sothat = A + A * ,Q = - .

    it ispossibleto formasymmetricmatri and

    heabovemanner.

    R beana lgebraof - rowedmatricesw ith

    sdesirableto haveassociatedwithevery

    mber (A )o f% w hichw ouldservethepurposeof

    dwouldbe attainedbyfindingascalar

    lementsarsofageneralmatri A suchthat

    ) isanon-constantrationa lintegra lfunction

    esuchthat

    ) (B ) .

    ( 2) b y t a i n g B = t h at ( A ) = { A ) 9 ( 1) ,

    c on s ta n t, ( 1 ) = 1 . H B = 0 , (2 ) g iv e s ( 0 )

    a in b e ca u se ( A ) i s n o t c on s ta n t, ( 0 ) = 0 .

    i n st a nc e , le t

    ( t)

    7 , T( 1 /< ) = / .

    ) ) = 1 , i t fo l lo w s th a t ( W ( t )) i s i n de p en d en t

    mberof theabovee uationwouldbeof

    e (W(t))hasforeveryva lueof tthesame

    0, namely

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    Determinants.

    ( V ) = i , ( T = ( T 2 ). i nc e ( T( t) ) 0( ( 1/ O )

    esamedegreeX intthat0(7(1/ / )) isin1// , it

    tbeamonomiala^ t7 in/ . ince (T(i))= 1,

    vo etheminimumprinciple(1)andassumethat

    fedbyactua llyobta iningunderthisrestrict iona

    enre uirements.Then

    1

    l). Hence

    r i , 9 ( TA ) = t d (A ) s o t ha t

    sa po lynomia linthee lementsw hich

    rinthe elementsofeachrow.

    { A ) , i t fo ll ow s th at

    gessignw hentw orowsarepermuted.

    ststatedwerecalledbyW eierstrassthe

    fadeterminant. B y1 .

    add, whenceby2 ,

    + eA , A i ... A J l A , fl 2A , < * n h = 0 .

    / > , & , . . .A is0if tw osubscriptscoincide, w hile if

    e al l d is t in c t, i e i, i ,. .. a c co r di n g as

    &

    ( 1 ) = i , i t f ol l ow s t ha t b 1, 2 = 1 . H e n c e

    A ,A , ... A . 1 A 1 2 A ,

    overa llpermutations(hl, hi, . . . , h )o f

    , ^ is1or 1accordingasthepermutation

    . H ense l: . re ineangew . Math. V o l. 159(1928)

    r : Z u r D et e rm i na n te n th e or i e. 1 8 8 1 8 87 W e r e

    2 8 . r o ne c e r : V o r le s un g en u b er d i e Th e or i e de r D et e r-

    t. se . Teubner1903.

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    dDeterminants.

    )satisfiesthedemandsofH enselwillfollow

    ptheentiretheoryofdeterminantsfromthe

    fW eierstrass1.

    ants. A s C ay ley remar ed, the idea

    array )precedesthatofdeterminant 2. A determin-

    dinaprecisewaywith anarrayofn2ordered

    wseemsto havebeencleartoC auchywho

    eatmentofdeterminants,atreatmentwhich

    pontoday3.Unfortunatelytheword deter-

    dayto meanbothanarrayanda number

    y . (Notetheremar sofMuirin 3, and

    fB ocher4. F oraveryclearstatementof the

    oremsfromthepresentpointofview,see

    br a , d e G ru y te r 1 92 . )

    esenttractforan e tendedtreatment

    practicallycompletebibliographyisgiven

    determinantsinthehistorica lorderofdeve lop-

    190 23. Theearlyhistory isattractively

    er, V orlesungeniiberdieTheoriederDeter-

    03 , p .1 9 . A n e c e ll e nt r e fe r en c e bo o i s

    E i n fu h ru n g in d i e De t er m in a nt e nt h eo r ie , e i pz i g

    arrayw ithelementsinaf ie ldgandletd(A ) or

    nant. A few importanttheoremsare listedforfuture

    d(A ).

    btainedfromA bytheinterchangeoftworows

    d ( A ) .

    sortwo columnsofA areidentical,d(A )= 0.

    ult,namelyinnotingthatthe hypothesis

    henced(A ) = 0, fa ilsw henghasthecharacter-

    odifiedtoincludethis case5ortheresult

    btainedfromA bymultiplyinganyrowor

    t h en d ( B ) = d ( A ) .

    s uarearrayeachelementofwhose throw

    , t + .. . + d s m (s = i , 2, . .. , n)

    sp e c. V o l .3 7 ( 19 2 7) p p . 43 3 4 3 a n d 45 7 4 5 8.

    ew . Math. V o l. 50(1855)pp. 282 285.

    y techn. V o l. 10(1815)pp. 51 112.

    mer. Math. MonthlyV o l. 32(1925)pp. 182 185.

    e in e a ng e w. M at h . V o l . 1 7 ( 1 93 2 ) p. 1 9 7.

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    dDeterminants.

    2 ) + . .. + d ( A m ) ,

    obta inedby replacingthee lementsof the throw

    n h . i m il a rl y f or c o lu m ns .

    sobtainedfromA byaddingtoanyrow(or column)

    heotherrows(co lumns), thend(B ) d(A ).

    ra y o f n ro w s,

    ar , k \

    a r,s

    ar S t

    norarrayofA . A rr " J isaprincipa lm inorarray.

    overthe i^ j w aysofse lectingthe numbersi1, . . ., i

    ,.. .,nwithoutregardto order,andthesign

    dingasthesubstitution

    .. ., i \

    .. r

    a rs . e tA r s de no te d ( A \ \ \ ' . . , r, Z \ \ r , \ \ . . . ) ,

    a c co r di n g as

    , . . . , n

    1 , . . ., n

    thecofactoro farsinA .

    a ip A i t= d p d ( A ) ,

    e r s d e lt a .

    ndB ben-rowedmatriceswithelementsina

    nm-row edminormatri o f theproductA B .

    erallselections ofi1,.. .,imfrom1,. ..,n

    = d ( A ) d ( B ) .

    d. ci. Paris1772.

    bra ictheories, p. 49. C hicago192 .

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    dDeterminants.

    fA isanm. narrayw ithe lementsina

    istheorderofaminors uarearrayofA o f

    determinantisnotzero1. fA iss uareof

    gisca lledthenull ityofA . 2

    s uarearrayofordern, withelementsina

    g = n , t h er e e i s t e a c tl y l i n e ar l y

    nsamongtherows(columns)ofA ,andcon-

    ofA sothatthefirst rarelinearlyindependent

    mnislinearlydependentuponthese.C all

    Thenev idently (A )= (B ). Thereare

    n de p en d en t r el a ti o ns

    + h gh e= hh

    r + 1 , . .. , n )

    B y Theorems7.5and7. 4every (r- - i)-

    eterminantwhichcanbe writtenasalinear

    ntseachhavingatleasttwoe ualcolumns,

    r.

    Theorem7. 8

    + . . .+ b p e B % + b pU B f t = 0

    thecofactorsB % 1are independentof , sothere

    + b p eC g h + bp hC h h = 0

    erforh > , C hh4= 0sinceB iso f ran .

    roflinearlyindependentlinearrelationsamong

    a st n g , s o r ^ g. H e n c e g = r, n r = .

    = 0 , g ( B ) + g ( C ) i n . Fo r e ve r y B t h er e

    ( B ) + g ( C ) = n .

    u a t i on A X = 0 o f r an n g ( A ) i s c al l ed

    teby( )thevectoror one-columnarray

    e n (y ) = A ( ) c a n be w r it t en f o r

    = 1 , 2 ,. .. , n) .

    ngew . Math. V o l. 8 (1879)pp. 1 19. Theconcept

    plicit , how ever, inapaperby . H eger: Den schr. A k ad.

    1 85 8 ) pt . 2 p p. 1 1 2 1.

    o p i n s Un i v. C i r c u l ar s V o l . l l ( 18 8 4) p p . 9 1 2

    V p p. 1 3 3- 1 45 .

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    dDeterminants.

    lu t io n o f th e e u a ti o n A B = 0 , a nd i f ( ) i s a n

    B ( )isthemostgenera lsolutionof the

    ctor(z)rangesoverthesolutionsof thee uation

    ) r e pr e se n ts e a c tl y ( B ) (A B ) l i n e ar l y in -

    n ( A B ) i n de p en d en t s ol u ti o ns o f t he e u a ti o n

    e a = n ( B ) s o l ut i on s ( z ) , ( z ) , . .. , ( zM ) o f th e

    f thesearee tendedby theso lutions(z( +1)), . . .. (zw )

    s o lu t io n s, t h e r a = ( B ) ( A B )

    1)), . . . , B (^ r))are independent. Forare lation

    ) + + C , B ( M) = B ( C + 1 (2 ' + 1 > )+ + C , (i ) )= 0

    .. .+ C , = C 1 (/ )+ + C ( iW ),

    = C T = 0.

    ,C arethreematricesofordern withelements

    ) q ( B ) + q (A B C ) .

    by B C . T he n A = > ( B C ) ( A B C ) i s

    ), (y ), . .. f o rw hichA B C (y )= 0andthe

    ( y ) , .. . ar e i nd e pe n de n t. T h en ( z ) = C ( y ) ,

    a ti s fy t h e e u a ti o n A B ( z ) 0 , a nd t h e ve c to r s

    ) , B ( z ) = C ( y ) , .. . ar e i nd e pe n de n t. B u t s i n ce t h er e

    ) ( A B ) s u ch v e ct o rs 1 ( /) , ( z ) , . .. ,

    ) .

    ofthe prdductoftwomatricesisat least

    therfactor,andat mostasgreatasthe sumof

    1.

    n iu s t h eo r em g i ve s ( A B ) ^ q ( B ) w he n

    ) ^ q ( B ) a nd w he n B = 7 , it g iv es

    ( A C ) .

    w eds uarematri w ithe lementsinadomainof

    ield% asasub-variety,thecolumn-nullity

    f isthenumberof linearly independentlinear

    nsofA withcoefficientsin^ .Thecolumn-

    erow-nullity3.

    eu B . A k a d . W i s s . 19 1 1 pp . 2 0 2 9 .

    w of n u ll i ty . o h ns H o p i n s Un i v. C i r c u l ar s V o l . 3 ( 1 88 4 )

    C o ll .W o r s V o l. V p p. 13 3 1 45 .

    nn. ofMath. i lV o l. 27(1925)pp. 133 139.

    mati . MacDuf fee.

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    dDeterminants.

    matri ofran ,andd A j ,...A is denoted

    m = ( ) , t h en t h e m- r ow ed s u a re m a tr i

    . 1

    o lumnsofA arrangedsothat >n = j = 0. The

    sare linearcombinationsof thef irst row s, so if suitable

    first rowsareaddedtoeachof thelast

    se lattermaybemadetoconsiste clusive lyof0 s.

    theran ofA ortheran ofB .N owbr,= 0

    theratio

    : bi m

    therw ords,

    metricmatri ofran thereisatleast onenon-

    forder . 2

    cof ran . B yTheorem8. 4set

    m P i , (t = 1 , 2 , . .. , m)

    s n ot 0 . e t b l c p ^ = m . T h en b i f = m pi p .

    b eo f ra n < g . H e n ce b k = j = 0 .

    ofas ewmatri iseven9.

    a nd b r = b sr . e t

    m P i = -mi P , p = \ = 0 .

    j p 2 t hi s im pl ie s

    p p i.

    , contrary totheassumptionthattheran o fA

    ors.Theorem9.1.A mongtheminorsof

    a tri A o forderntheree iststherelation5

    . 27A | t

    i , m + 2 , . . ., 2 m h = m + i , . .. , 2m

    i , h = m + i , h 1 , m, h + i ,. .. , 2m .

    ente lements. et ar, = a . Theoperation

    ihrungindieDeterminantentheorie, p. 124.

    e a ng e w. M at h . V o l . 72 ( 1 87 0 ) pp . 1 52 1 7 5.

    e w. M at h . V o l .2 ( 1 82 7 ) pp . 3 47 3 5 7.

    ebyG. A . B liss: A nn. o fMath. I V o l. 1 (1914)

    . p r eu B . A k a d. W i s s. 1 88 2 I pp . 82 1 8 44 W e r e

    3 9 7.

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    dDeterminants.

    ofcolumnh byelementswiththesamefirst

    nd subscriptm,andthenreplacesthe elements

    eterminantbyelementswiththesame second

    ssubscripth. C onse uently

    I h

    alto

    4 = w i n t he s e co n d su m ma t io n . Fo r h = j , = = 0 .

    symmetric. Thecoef f iciento fah , h= \ = , is

    mh 8 au /

    o fcolumnshand doesnota lterthise pression,

    tireleftmemberreducesto1

    o ne c e r s i d en t it i es w as g i ve n b y . c h en -

    provedthemfrom now nidentitiesina lgebra ic

    m e4statedthattheyare impliedinGrass-

    u s de h nu n gs l eh r e 1 8 2 , p .

    talllinearrelations amongtheminorsofa

    nearlydependentuponthoseof ronec er,

    dentsystems.H ealsoprovedthatno such

    w matrices. Hisresultsaresignif icantincon-

    ationsof ronec er sidentit iesbyMuir ,

    licatedidentitiesamongtheminorsof

    ronec er sinthesymmetriccase. A very

    entitiesamongtheminors ofamatri was

    . B eaver9.

    oc . N a t. A c a d. c i. U . . A . V o l. 12 ( 19 2 ) p p. 3 - 4 .

    a th . P hy s i V o l . 32 ( 1 88 7 ) pp . 1 19 1 2 0.

    l . A m e r. M at h . o c . I V o l . 2 ( 1 89 ) p p . 13 - 1 38 .

    h. A n n V o l .2 ( 18 8 ) p p. 2 09 2 10 .

    eangew . Math. V o l. 93(1882)pp. 319 327.

    o l . 3 (1 9 02 ) p p. 4 1 0 4 1 .

    N a t . A c a d . c i . U. . A . V o l . 12 ( 1 92 ) p p . 39 3 3 9 .

    . Math. oc. V o l. 2(1901)pp. 395 403.

    m e r . Ma t h. M on t hl y V o l . 3 9 ( 19 3 2) p p . 2 6 2 7 .

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    dDeterminants.

    ow edthatthereare ustn2 n+ i

    norsofamatri . touf fer3showedthat(A J ,

    nstitutesuchasystem, thesubscriptsindicatingdeleted

    f fer4gaveamethodfore pressingthedeter-

    nyorderintermsofnotmorethan14of its

    der,andlater5 showedthatthedeterminant

    afunctionof fourminorsofordern 1 andone

    genera ltheoremonthee pressionofadeterminant

    inantsw asprovedbyW. W . F le ner .

    m10. 1. fA ise itherageneralmatri o r

    ,thereisno identity

    ai ),

    mialsintheelementsofA neitherofwhichis

    of A i n de p en d en t a nd d ( A ) = f g . i n ce

    ye lement, if auoccursin/ itdoesnotoccuring.

    insa11arl, hencegiso fdegree0ineveryarl.

    onta insarsarl, giso fdegree0ineveryar, and

    lyaslightmodificationisre uiredtoe tend

    ymmetricmatri 7.

    theoremthat thedeterminantofan

    isanirreduciblefunctionofthevariables8.

    minantofthegenerals ewmatri ofeven

    rationalfunctionof itse lements.

    n 2,andtheprooffollowsby induction.

    \ i s s e w of o dd o rd er a nd h en ce i ts r an i s n 2 a t mo st .

    f b e th e co fa ct or o f ai f in 4 ; ; ; ; ; | | l . A s

    5,

    tionoftheelementsofA .B yassumption

    areofarationalfunctionof thea^ , sothesamemust

    beta enas1. B y the aplacedevelopment

    a ^ a n = p ta in )2 .

    altheoremwasprovedby .Z ylins i9.

    ta inedf romA = (ars)by replacingacerta in

    s . R o y . o c . o n do n V o l . 1 85 ( 1 89 3 ) pp . 1 11 1 0 .

    o l. 38(1894)pp. 537 541.

    er . M at h . o c . V o l .2 ( 1 92 4 ) pp . 3 5 - 3 8 .

    h. MonthlyV o l. 35(1928)pp. 18 21.

    t h. M o nt h ly V o l . 3 9 ( 19 3 2) p p . 1 5 1 6 .

    n n . of M a th . I V o l . 2 9 (1 9 27 ) p p. 3 7 3 37 .

    t iontohighera lgebra, p. 177. Macmillan1907.

    bra ictheories, p. 259. C hicago192 .

    B u l l . in t . A c a d. P ol o n. c i . 19 2 1 pp . 1 01 1 0 4.

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    dDeterminants.

    of matrices,aswasclearlyshownby

    sideredasa linearvectorfunction. . D. B ar-

    neousvectorfunctionsofdegreep.H estates

    rcterist icroote istsforthegenera lizedmatri .

    beenatta inedine tendingtohigherdimensions

    thesenseofhypercomple numberinw hich

    inceeveryassociativesystemcanberepresented

    almatrices,thislac ofsuccessis notsur-

    ensionalarrayshavereceivedsomeattentionin

    rformsandtensoranalysis.Theirimpor-

    eneralizationsofran whichcanbeapplied

    utativesystems.Determinantsofma-

    uaternionswerediscussedbyH amilton4.

    determinantofamatri o f uaternionsby

    chtermin theorderoftheir columnindices.

    dbi uaternionsandtri uaternionsasmatricesw ith

    . tudy7gaveabriefdiscussionofmatrices

    belongtoadivisionalgebraor non-com-

    derableimportancefromthetheoremof

    8thateverysimplea lgebracanberepresented

    whoseelementsbelongtoadivisionalgebra9.

    overadivisionalgebrain connection

    sof lineare uationswereconsideredby

    . H ey ting11, and0. O re12. The latterdef ines

    ntby

    ^ O ) + a nA ^ > + . ..+ , ^ / ) ,

    tionsofthehomogeneousleft-hand

    )

    e r . . M at h . V o l . 49 ( 1 92 7 ) pp . 8 9 9 .

    a lif orniaPubl. Math. V o l. 1(1920)pp. 321 343.

    . Math. Physics, Massachusetts nst. Techno l. V o l. 7

    5 . - R i c e, . H . : b i d. 1 9 28 p p . 93 - 9 .

    o f uaternions(A ppendi ). ondon1889.

    . A m e r .M a th . o c .i l V o l . 5 ( 18 9 9) p p . 33 5 3 3 7.

    oc . o nd on M at h. o c. I V o l . 4( 19 0 ) p p. 1 24 1 30 .

    at h . V o l .4 2 ( 19 2 0) p p . 1 6 1 .

    M . : Pr o c. o n do n Ma t h. o c . I V o l . ( 1 90 8 ) p. 9 9 .

    brenundihreZ ahlentheorie , p. 120. Z urich1927.

    . : Me s s. M a th . V o l . 55 ( 1 92 ) p p . 14 5 -1 5 2 P r oc .

    V o l . 28 ( 1 92 8 ) pp . 3 95 - 42 0 .

    A n n . V o l . 98 ( 1 92 7 ) pp . 4 5 4 9 0.

    M a th . V o l . 32 ( 1 93 1 ) pp . 4 3 - 47 7 .

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    ce uation.

    right-e uivalentiftheirrightdeterminants

    ricesA andB areright-e uivalentif they

    of tw orow sorof tw ocolumns orifA is

    iplyingtheelementsofacolumnon theleft,

    ontheright, w ith = j = 0 orifA isobta ined

    wto anotherroworonecolumnto another

    ce uation.

    t ion. fA isamatri o fordernovera

    , A 2, . . ., A * ' constituten2+ 1setsofn2

    arelinearlydependentin ThusA satisfies

    11 - 1+ . . . + mf = 0

    minimumdegreefi.W eshallcallfi theinde

    ca l ar m a tr i i s 1 . v e ry m at r i e c e pt 0 h a s

    0,m ).) f ' /.)

    ) m ( X ) + r ( X ) w h e re r ( ) .) = 0 o r e ls e r ( A ) i s o f

    ) = m ( A ) = 0 , r ( A ) = 0 . i n ce f i w as m i ni m al ,

    nmume uationm(/ .)= 0isuni ue.

    nimume uationwillbecalledthe norm

    uation. Thematri obtainedf romA = (ars)

    thecofactorA , ro fasrisca lledthead o int

    a tr i A A j d ( A ) i s c a ll e d th e i nv e rs e o f A , w r it t en

    o re m 7 .8 ,

    * ( i4 ),

    tisfiesane uation

    C ^ * - 1 + . .. + C = 0 ,

    goniermatriceswithe lementsinaf ie ldthenA

    p l)=0 w hosecoef ficientsare in

    consideredasan - thordermatri w hose

    sin ofdegree^ k . tsad o int

    - + D ^ -D -i + . .. +

    ngew . Math. V o l. 84(1878)p. 1 3.

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    ce uation.

    o fdegree^ k (n 1). Then

    p 1 l - l + .. .+ p n

    e

    p( X ) ,

    k - V = Z P n- X " I ,

    . h m .

    minate.By e uatingcoefficientsofthepowers

    a ti o ns a r e ob t ai n ed . f t h e A - t h e u a ti o n is m u lt i pl i ed

    eresults added,thesummaybewritten

    - 1) -i y ,C k - A *

    eoremof H .B .Phillips1whoproved

    e - t h or d er m a tr i c es , a nd B . . ., B k a r e ma t ri c es

    that

    B k = 0 ,

    j 1+ . . . + A M w heref t, . .. . & are in-

    venis similartoFrobenius 2prooffor

    attributestheidea toPasch3.

    ymatri satisf iesitscharacterist ice uation

    lton-Cayleytheorem,establishedfor

    H amilton4, andprovedforn= 2, 3byA . C ay -

    minthe generalcasewiththecomment

    tounderta eitsproof.Manyproofs,more

    beengiven . A . R . F orsyth7applieddifference

    . B uchheimmadetheproofessentia lly in

    statingthatit wasta eninconceptfrom

    81.

    e r. . M a th . V o l . 41 ( 1 91 9 ) pp . 2 6 2 7 8.

    eu B . A k a d . W i s s . 18 9 p . 0 .

    o l. 38(1891)pp. 24 49.

    ectureson uaternions, p. 5 6 . Dublin1853.

    o s . Tr a ns . R o y . o c . o n do n V o l . 14 8 ( 18 5 8) p p . 17 3 7 .

    F o le p ol yt ec hn . V o l. 25 ( 18 7 ) pp . 21 5 2 4 C E u vr es

    2 33 .

    sMath. V o l. 13(1884)pp. 139 142.

    t . V o l . 13 ( 1 88 4 ) pp . 2 6 6 .

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    ce uation.

    orem14.2, itshouldbenotedthatB uch-

    ts o f t he e u a ti o n X I A = 0 a r e ro o ts

    e f io fA is^ n.

    uationofA forthee uation X I A = 0

    eftmemberiscalledthe characteristicfunction

    + t tX * - t n= 0

    ationofA , thenttisthesumofa lltheprincipal

    l i n X I A = 0 i s t h e su m o f th e d et e r-

    a inedbysuppressingn irow sof A

    umns.

    )= au+ + anniscalledthe trace

    ntionofA secondonly inimportanceto tn= d(A ).

    uationofdegreenwith coefficientsin% is

    t ionofsomematri o fordernw ithe lementsin

    onbe

    - + . .. + b n= 0 .

    ar a ct e ri s ti c e u a ti o n. F or i f i n t he m a tr i X I B

    lumnbyX andaddstothe(n lmth, multiplies

    m th c o lu mn o f t he n e w ma t ri b y X a n d a dd s t o th e ( n 2 m th

    pment, thedeterminantof thismatri isseen

    n do n M at h . o c . V o l . 1 ( 18 8 4) p p . 3 8 2 .

    s d a n al y se e t d e ph y si u e ma t he m at i u e V o l . ( 1 84 0 )

    I V o l .1 1p p. 75 1 33 .

    a th . V o l . 21 ( 1 87 ) p p . 17 8 1 9 1. a i sa n t, C . A . :

    e V o l . 17 ( 1 88 9 ) pp . 1 04 1 0 7. R a d o s , G. : Ma t h. A n n .

    24.

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    ce uation.

    ( o r it s n eg a ti v e) a B e g l e it m at r i " . W e s h a ll

    gitthecompanionmatri o f thee uation

    educible in% , say

    ( - * y ,

    t, le t

    en t t ha t d (X I ) = f ( X ) . T h is m a tr i / w i ll

    ri 2.

    m inimume uation. Theorem15.1. et

    erist ice uationofA , andleth(X )bethegreatest

    i ) -r o we d m in o rs o f 7 .1 A . T h en

    0

    onofA . 3

    = C ( X ) . T he n C A ( X ) = h (X ) ( X ) w he re t he e le me nt s

    pr im e. i nc e / (A ) = C ( X ) C A ( X ) ,

    X )h X ) ( X ),

    o ,

    ) ( X ) .

    ( A ) 0 a nd m ( X ) g ( X ) w h er e m (X ) = 0 i s t h em i ni -

    (f i) = ( X f ) ( X , u ), w eo bt ai n

    X I ) -m( A ) = C ( X ) ( X I , A ) .

    e nc e

    ) ( X I , A ) ,

    h (X ) g (X ) ( X I , A ) .

    ecance led. inceg(X )div ideseverye lement

    eelementsof (X ) arere lative lyprime1g(X ) m(X ).

    H e i d e lb e rg . A i a d . W i s s. V o l . 5 ( 1 91 8 ) p. 3 - M at h . Z .

    5.

    es u b st i tu t io n s et d e s li u a ti o ns A l g ^ b r i u e s, i v re 2

    s 1 87 0 .

    ngew . Math. V o l. 84(1878)pp. 1 6 3.

    at h . A n n . V o l . 4 ( 1 90 ) p p . 24 8 -2 3 .

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    ce uation.

    s t he c o mp a ni o n ma t ri ( o r t h e o r da n m at r i )

    0 i s t he m i ni m um e u a ti o n of B ( o r ) .

    m inimume uationofB isl i ew ise itschar-

    t h e fi r st c o lu mn a n d la s t ro w o f A / i ,

    1isobtainedw hosedeterminantisf reeofX X i.

    n lmrow edminordeterminantsofX I is

    uationof / isl i ew ise itscharacterist ice uation.

    tfactorsofthe characteristicfunction/(/)

    lein% coincidewiththedistinctirreduciblefactors

    (X ).

    rem15. 1,

    ) 0isarooto f / (X )= 0, soevery irreducible

    X ). F rom(15. 1)

    ) .

    , /, r,< ui.

    m (X ) n .

    )= 0isarooto fm(X )= 0, andevery irreducible

    X ). 1

    erd(A )orn(A )vanishes, bothvanish.

    singularornon-singularaccordingasn(A )= 0

    ogatory2if itsinde f i islessthann.

    non-singularofordern andinde fi,A 1is

    r ee f i 1 . 3

    ationofA be

    1 ' A - 1+ + m ^ X + n (A ) = 0 .

    + m1 A P - 2- h m f, -1 ) n (A ) .

    .B utA A 1= A 1A = ,soA B = A A \

    \ B = A \

    singularoforder nandinde fi,theree ists

    ib l e as a p o ly n om i al i n A o f d eg r ee f i 1 s u ch t h at

    w, A * - H h m J ) ,A B = B A = n (A ) = 0 .

    matri ise ithernon-singularoradiv isoro f zero .

    )= 0isthe minimume uationofA ,then

    fm(X ) andf (X )haveacommonfactoro f

    n: A lgebrenundihreZ ahlentheorie , p. 21. Z urich1927.

    c a d. c i ., P a ri s V o l . 9 8 ( 1 88 4 ) pp . 4 71 4 7 5 .

    po l yt e ch n . V o l .2 5 ( 18 7 ) p p. 2 1 5 2 4 .

    e in e a ng e w. M a th . V o l . 1 27 ( 1 90 4 ) pp . 1 1 1 6 .

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    ce uation.

    ) ( A ) , f ( A ) = h ( A ) ( A ) , h ( A ) o f d e g re e ^ 1. T h en

    / i a nd ( A ) 4 = 0 . T he n

    ( A ) ,

    en/ (/ ) isa lsosingular.

    fm(X )and/ (A )sothat

    ( X ) f ( X ) .

    (^).

    ) isa lsosingular, andh(A ) isnotaconstant.

    ,y, ,...)= / rational

    )

    terminates , y , z, . . . , w herepand arepo ly-

    e X , B o f i nd e f i , C o f i n d e v , .. . b e co mm u ta t iv e

    , B , C , . . . ) isnon-singular. Thenr(A , B , C , . . . )

    canberepresentedasa polynomialofdegree

    < f i i n B , o f d eg r ee O i n C , . . .

    , C , . . . isbuiltupby theoperationsofad-

    ca larmultiplication. inceA , B , C , . . .

    ulta teachstepisuni ue. ince (A , B , C , . . .

    stsandisapolynomia lin , andtherefore in

    e p l = l p , an d r i s un i u e ly d e fi n ed . B y u s i ng

    ofA , B , C , . . . , thedegreeof rmaybereduced

    ts. etA beamatri o fordernw ithe lements

    X I A be itscharacterist icfunction.

    f% inw hich/ (A )= 0iscomplete ly reducible .

    )= 0arecalledthe characteristicroots1.

    ,B ,C ,... becommutativematrices,andlet

    onalfunction.Thecharacteristicrootsa1,...,anof

    . canbesoorderedthatthecharacterist icrootsof

    b 1 , cl , .. . ), . .. , /( , b , c n , . .. ) . Th i s or d er -

    unction/.2

    a s) ,P (o ) = J J ( a> b ) ,y (< w ) = J ( w c ) ,. ..

    onsofA , B , C , . . . respective ly. Write

    (a (, b , c , .. .) = / ( , b , c , .. .) f (f li ,b ' , c , .. .)

    f ( , b , c , ., .) H = ( - ai )f i k . .. + i y b ^ g i i c. ..

    k . . . T he re fo re

    , c , . .. ) = < x ( ) + ( 3( y) + M y (z ) + . .. ,

    ,i , = i , . .. , v, . ..

    ester.

    eu B . A k a d. W i ss . 18 9 1 p p. 0 1 6 1 4 .

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    ce uation.

    aecommutative , thesetw opo lynomia lsgivee ua l

    , y = B , z = C , . .. H e n c e

    f (A , B , C , . . . ) . Thereforetheminimum

    , . . .) , o fdegreean, ise ua ltoaproductof

    ncludeallthe distinctfactorsofthecharacteristic

    , B , C , . . . areorderedbyca llingthe i- th

    f = 0 /( ( , < , c i, .. .) .

    arried throughwhen/isa polynomial

    1 , i n y of d e gr e e fi 1 , i n z o fd e gr e e X 1 , .. .

    cients,andanorderingoftheroots of

    ined. B y Theorem15. every rationa lfunction

    obta inedbyspecia lizingthecoef f icientsof

    gisthe sameforallrationalfunctions1.

    ovedthatthecharacterist icrootsofA nare

    hecharacterist icrootsofA . Thespecia lcaseforA

    redby . . y lvester3. W. pottisw oode1

    1arethereciproca lso f therootsofA . G. F ro -

    1 . 1f irstforasinglematri andlaterinthe

    errediscovered pottisw oode s7resultand

    1878.

    mwich9notedthatFrobenius theoremneednot

    alfunction.

    acteristicrootsofA B arethesameasthose

    . 9thecoef f iciento f^A " - inthecharacter-

    i s

    . - B . p r eu B . A k a d .W i s s . 19 0 2 1 pp . 1 20 1 2 5.

    . r e in e a ng e w. M a th . V o l . 30 ( 1 84 ) p p . 38 4

    V o l . 12 ( 1 84 7 ) pp . 5 0 6 7 .

    o u v . A n n . ma t h. V o l . i l (1 8 52 ) p p. 4 3 9 4 4 0.

    . r e in e a ng e w. M at h . V o l . 51 ( 1 85 ) p p . 20 9 2 7 1 an d

    eangew . Math. V o l. 84(1878)pp. 1 6 3.

    . A c a d. c i ., P ar i s V o l . 9 4 (1 8 82 ) p p. 5 5 5 9 .

    M ag . V V o l . 1 ( 1 88 3 ) pp . 2 7 2 9 .

    . ' A . : P r o c. C a m b ri d ge P h il o s. o c . V o l . 11 ( 1 90 1 ) pp . 7 5

    g .V V o l . 1 ( 1 88 3 ) pp . 2 7 - 2 9 .

    b , c , ... ) = 0

    c , .. .) .

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    ce uation.

    nd(A 1, . . . , h i)rangeovera llf j se lections

    eset1,2,...,nwithoutregard fororder.

    nterchangingthesummationindices.

    oremwithoutproof.A proofbasedupon

    tyw asgivenbyH. . Thurston1. A proof

    T u rn b ul l a nd A . C . A i t e n 2.

    atthetheoremofFrobeniusaffordsan

    Tschirnhausentransformation. etit

    e uationw hoserootsaretherationalfunctiony

    . e t B b e t he c o mp a ni o n ma t ri o f f ( ) = 0 .

    p(B ) = 0 isthere uirede uation.

    bra icintegra lroots, thee lementsofB arerationa l

    o lynomialw ithrationa lintegralcoef f icients,

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    ce uation.

    + A n t h e a d o i nt - tr a ce o f A 1 , s i nc e i ts s u m wi t h A 1

    edef init ionofcon ugatesetby theomis-

    andshowedthatforeveryA 1asetof generalized

    ists, nota lw aysuni ue ly , how ever. ater2hegave

    ndinga llsetsofcon ugatesforagivenmatri .

    particularmatri B suchthatofB form

    gatematricesinthesenseof Taber,whereto

    nity.

    tthefield generatedbytherootsofany

    phicwiththefield generatedbythematric

    acterist icroots. nthisparagraphgis

    tA cdenote(ars), obta inedf romA by replacing

    ugatecomple number.

    ianifH = H C T.5A realhermitianmatri

    w-hermitianif = C T. A reals ew-

    ew .

    U1= U T.7A realunitarymatri is

    t or y i f V 1 = V , i . e . , if V 2 = 1 . 8

    hastwoofthethree .propertiesinaset,

    ary.

    al,involutory.

    volutory.

    utonne9,thelasttwotoH .H ilton10.

    atri isuni uelye pressibleA H +

    nd iss ew -hermitian.

    heorem5.3.

    H + whereH ishermitianand iss ew-

    arethema imaof theabso luteva luesof the

    M a th . I V o l . 2 3 (1 9 23 ) p p. 9 7 1 0 0.

    h. Physics, Massachusetts nst. Techno l. V o l. 10(1932)

    er. Math. MonthlyV o l. 39(1932)pp. 280 285.

    m e r . Ma t h. o c . V o l . 3 ( 1 93 0 ) pp . 2 2 2 4 .

    . A c a d. c i ., P ar i s V o l . 41 ( 1 85 5 ) pp . 1 81 1 8 3.

    e in e a ng e w. M a th . V o l . 1 22 ( 1 90 0 ) pp . 5 3 7 2 .

    d . C i r c. m at . P al e rm o V o l . 1 ( 1 90 2 ) pp . 1 04 1 2 8.

    n n . V o l . 13 ( 1 87 8 ) pp . 3 20 3 7 4. P r ym , F. : A b h . G es .

    3 8 ( 18 9 2) p p . 1 4 2 .

    c. Math. F ranceV ol. 30(1902)pp. 121 134.

    eneouslinearsubstitutions. Ox ford1914.

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    ce uation.

    respectively , andifa= + P isacharacteristic

    ^ . nh, f3 ^ n .

    i s s in g ul a r, t h er e e i s ts a v e ct o r ( ) = ( l , .. . , n )

    oa l l 0 su c h th a t (A a ) ( ) = 0 . H e n c e

    . ( , / = 1, 2 ,. .. . n)

    a j ( } ,

    a. i 5,. X j .

    acting,

    ^ ^ i h.

    f r i X , .

    + n) s m(V + + * ) ,

    n h, f i * n .

    racteristicrootsofan hermitianmatri are

    = 0 , = 0 , a nd e ve ry / | = 0 .

    tsofareal symmetricmatri areall

    hy2. Many laterproofshavebeengivenby

    uchheimetc. Thee tensiontomatricessuch

    adebyH ermite3andresultedinsuchmatrices

    racteristicrootsofa s ew-hermitianmatri

    .

    a = 0 .

    ors ewmatricesbyA .C lebsch5and

    . H i r sc h : A c t a ma t h. V o l . 25 ( 1 90 1 ) pp . 3 7 3 7 0.

    n c ie ns x e r c is es . 18 29 1 83 0 C o l l. W o r s I V o l . 9 pp . 17 4

    c a d. c i ., P ar i s V o l . 4 1 (1 8 55 ) p p. 1 8 1 1 8 3.

    mericieA lgebrepp. 133 179. Messina1921.

    in e a ng e w. M a th . V o l . 2 ( 1 8 3 ) p p. 2 3 2 2 4 5.

    . - B . p r eu . A k a d . W i ss . 1 87 9 .

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    ce uation.

    thelasttheoremis real,then

    # ,) / a r e al l r ea l , th e i ne u a li t y (1 8 .3 ) m ay b e a pp l ie d

    1 i ( n- i) v i. -

    < 2 3> J k . 1

    wasprovedby .B endi son2,andthe

    eemstohaveinspiredthew or o fH irsch.

    a- -if beacharacteristicrootof A = H + .

    emistheleast andMthegreatestofthe char-

    hermitianmatri H bedenotedbyhrs.

    ueof theratio

    e independentcomple variables. Thegreatest

    )assumesarecharacterist icrootsofH, for

    f + f y , th e c on d it i on s

    2, . .. , )

    f ^ x ^ = 0.

    mvaluewhich/ ( )assumesandMisthema i-

    otM. 3

    plicite pressionfor and/ f romw hich

    smaybederived.

    ine ua lit iesbyanothermethod.

    arebyA . H irsch: 1. c.

    c t a m at h . V o l .2 5 ( 19 0 1) p p . 35 9 3 5 .

    son, thecomple casebyHirsch: 1. c.

    t h. V o l . 30 ( 1 90 ) p p . 29 5 3 0 4.

    n n . V o l . ( 1 90 9 ) pp . 4 88 - 51 0 .

    mati . MacDuf fee. 3

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    ce uation.

    thatifA isacharacterist icrooto fA andifm

    testcharacteristicrootof thehermitian

    n m= S X X M .

    heelementsofA areallrealandpositive,

    whichisreal,positive,simple,and greater

    other characteristicroot.

    ofthe minimume uationofanhermitian

    H hastheminimume uation

    ) ,

    - 1h X ) .

    ) 2.Thematri H 1= hr,)= m1(H )ishermitian,and

    0 . B u t

    (H) = 0. B utm1(X )iso f low erdegreethan

    mption > 1leadstoacontradiction3.

    ofunitarymatrices.Theorem19.1.The

    tarymatri areofabsolutevalueunity.

    c r oo t o f th e u ni t ar y m at r i U , + i l i s a

    r U + U 1 = 1 7 + UC T , a n d i x i s

    m it i an m a tr i U U 1 = U U C T b y T he o re m

    laries18. 31and 8. 32,

    i x = 2is,

    tis,

    x = r i s,

    sgivenbyR . B rauer5. fU= (ur, ) is

    1, sothee lementsofUareboundedinabsolute

    retrueof thecoefficientsofthecharacteristic

    sroots. B utU1andU are li ew iseunitary ,

    sof Ularethereciprocalsof thoseofU,

    U arethe - thpowersof thoseofU . Unless

    U wereofabsolutevalueunity,somepositive

    d bemadearbitrarilylarge,thusleadingto

    l. A m er . M at h . o c . V o l . 34 ( 1 92 8 ) pp . 3 3 3 8 .

    eu B . A k a d . W i s s . 19 0 8 pp . 4 71 4 7 .

    M . : A n n . o f Ma t h. I V o l .2 7 ( 19 2 ) p p . 24 5 2 4 8.

    uMath. . V o l. 28(1927)p. 281.

    u M a th . . V o l . 30 ( 1 92 8 ) p. 7 2 .

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    n t eg r al M a tr i c es .

    C T = V C T V , a n d if i s a ro ot o f U V \ = 0 ,

    w here^ isthegreatestinabso luteva lueand

    lueof thecharacterist icrootsofV . ach

    ncipa lm inorofaunitarymatri iss lin

    ple characteristicrootsofanorthogonal

    a lpa irs2.

    e uationofanorthogonalmatri hasrea l

    rootsoccurincon ugatepairs, w hichby

    alpairs.

    oremhavebeengivenbyA . . R ahusen3

    connectionw iththisla tterpaperseea lsoG. V ita li5.

    a t if A + l = 0 h a s r e ci p ro c al r o ot s , A

    utory.

    aif thecoef ficientse uidistantf romthe

    e u at io n of A a re e u al , A + A h - - l = 0

    thesecoefficientsoccurin pairswithopposite

    A + l = 0 h as a ll r ea l ro ot s.

    n t eg r al M a tr i c es .

    sina principalidealring.A commutative

    ois calledadomainofintegrity.A domain

    nt1 inwhicheverypairof elementsnot

    mondivisorrepresentablelinearlyinterms

    principalidealring9.

    , anumberw hichdiv ides1isca lleda

    whereuis aunitisreciprocal,and two

    darecalledassociates.A setofnumbersof

    ssociatedbutsuchthat everynumberof

    hemiscalledacompleteset ofnon-associates

    egersand 0constituteacompletesetof non-

    tionalintegers.

    her0noraunit isprimeorcompositeaccording

    esnotimply thatborcisaunit.

    B r a u e r: T o ho u M a th . . V o l . 3 2 ( 19 2 9) p p . 44 4 9 .

    , p ur e s ap p l. V o l . 1 9 ( 18 5 4) p p . 25 3 2 5 .

    i s u n di g e O p g av en V o l . 5 (1 8 93 ) p p. 3 9 2 3 9 4.

    n . Ma t . t a l V o l . ( 1 9 27 ) p p. 2 5 8 2 0 .

    . Ma t . t a l. V o l . 7 ( 1 92 8 ) pp . 1 7 .

    o l l . U n. M at . t a l. V o l . ( 1 9 2 8) p p . 5 - 9 .

    c c a d. n az . i nc ei , R e nd . V I V o l . 8 (1 92 8) p p. 6 4 6 9 .

    u M a th . . V o l . 32 ( 1 92 9 ) pp . 2 7 3 1 .

    oerneA lgebraV o l. pp. 39and 0.

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    n t eg r al M a tr i c es .

    faprincipal idealringisa euclideanring

    operties:

    ye lementa(e ceptpossibly0)o f thering,

    gers(a)called thestathmofa.

    ersaandb, b^ 0, theree isttw onumbers

    b + r , a nd e i th e r r = 0 o r e l s e s( r ) < s ( b ) .

    ple numbersa+ ib,astathmis

    mialdomain% ( )o facommutativef ie ld r,

    alservesas astathm.Forthetrivialinstance

    enas1foreverya. A euclideangreatest

    istsineveryeuclideanring.

    roperifit isnota fieldandifa stathm

    hats(ab)= s(a)s(b)foreveryaandb. ince

    )s(b), e ithers(b)= 1foreverybsothatdiv isionisa lw ays

    d, ore lses(0)= 0. C onverse ly lets(a)= 0.

    reveryb, b= a , and isaga inaf ie ld.

    )= s(1)s(b), e ithers(b)= 0(and(5isa f ie ld)or

    nit, anduv= i. Thens(u)s(v)= 1 sothat

    s(a)= 1, a isaunit, f orthestathmof the

    nynumberbyamust be< 1andhencebe 0.

    nrings(a)= 0ifandonly ifa= 0,s(u)= i

    nds(a)= s(b)ifandonly ifaandbareas-

    theseto fa ll - thordermatricesw hoseelements

    lring sub ecttotheoperationsofaddit ion

    3. 2 { isaringbutnotaprincipa lidea lring.

    sca lledunimodularoraunitmatri if andonly

    U o f 9 tt s u ch t h at U U = .

    matri ifandonlyif d(U)isaunit of

    U)d(U )= 1sothatd(U)isaunitof

    andd(U)isaunito f ty, thenU1isin D and

    definit ion.

    A ofW tisa divisorofzeroif andonlyif

    matri B o fTheorem15.4(suchthatA B

    in 2 R .

    adiv isoro f zeronoraunit isca lledprimeif

    impliesthate itherB orC isaunit. Matrices

    unitsnorprimesarecalled composite.

    ositematri canbee pressedasaproductof

    primes.

    3 . . .,

    d e rb u rn : . r e in e a ng e w. M a th . V o l . 1 7 ( 1 93 1 ) pp . 1 29

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    n t eg r al M a tr i c es .

    atri implies

    ) d (A 3 ) . .. .

    aunit. Thatis, eache lementinthese uence

    . d(A 2)d(A 3)d(A 3). . .

    receding. uchase uencecanconta inbut

    s1.

    odularmatrices.Theorem21.1. et

    numbersofaprincipa lidea lringw ithgreatestcom-

    istsamatri ofdeterminantdnhavinga1,a2,...,an

    ueforn = 2. upposeittrueforn 1,

    whichhasa1, a i, -1asitsf irstrow , and

    g. c. d. d -1of 1, a2, .. . , an - . Determinep

    a n = d n. C o n s i de r t he m a tr i D o b t a in e d by

    htbya , 0, . . . , 0, 0andthenbelow by

    2 A * n -1 . - n - 1 R > - 1. P. Th en d D n) = d n

    givenby . Weihrauch4, B ianchi5, and

    genera lly thatamatri canbefoundw ith

    , an2, annandadeterminant+ 2an2-

    sarearbitrary.

    eralizedasfollows.A p.narrayofrational

    , andtheg. c. d. of thep- row edminordeterminants

    betoaddn prow sof integerstothisarrayso

    earraysha llbeofdeterminantd. H . . . m ith8

    9provedthistheoremanddetermineda llpossible

    hortproofby induction.

    . Tw omatricesA andB areca lledle f t

    saunitmatri UsuchthatA = UB . The

    beusedtoe pressthisre lationship, w hichpossesses

    e ua lity re lationship, namely10:

    d er n e A l g eb r a V o l . p . 4

    3, G. isenste in: . re ineangew . Math. V o l. 28

    74. F oranyn, C . H ermite : . Math, puresappl. V o l. 14

    0 .

    o c . Ma t h. F r an c e V o l . 50 ( 1 92 2 ) p. 1 0 0 1 1 0.

    M a th . P hy s i V o l .2 1 ( 18 7 ) p p . 13 4 1 3 7.

    su l la T eo r ia d e i N u m er i A l g e b ri c i, p p . 1 7 .

    m e r. M at h . Mo n th l y V o l . 31 ( 1 92 4 ) pp . 1 1 1 2 .

    ng e w. M a th . V o l . 40 ( 1 85 0 ) pp . 2 1 2 7 8.

    Ph il os . Tr an s. R o y . o c. o nd on V o l . 15 1 (1 8 1 1 8 2 )

    . : A n n . F ac . c i . Un i v. T o ul o us e V o l . 4 (1 8 90 ) p p. 1 1 0 3.

    r. Math. oc. V o l. 37(1931)p. 538.

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    n t eg r al M a tr i c es .

    r A = 5 o r A = f = B .

    A .

    i m p li e s B = A .

    a n d B = C , t h en A = C .

    orthere lationA orA = B U.

    operationsupontherowsofamatri can

    plyingthematri ontheleftbyanelementary

    i obtainedbyperformingtheelementary

    tionupontheidentitymatri /.

    worows.

    ee lementsofarow byaunit of

    mentsofany row of t imesthecor-

    yotherrow,where isin

    isaunitmatri w hose inverse isan

    esametype. fB isobta inable f romA bya

    rytransformations,B = A .1

    atri A withelementsin< J 3isthe leftassociate

    sabovethemaindiagonal, eachdiagonale lement

    mofnon-associates,andeachelementbelowthe

    rescribedresiduesystemmodulothediagonal

    w illbesa idtobe inH ermite snormalform.

    e lementsin ithereverye lementof the

    atleastonenon-zeroelementwhichbya

    nbe putintothe(n,n)-position. etdnbe

    thelastcolumn,andsupposethat

    nn = 4 .

    e istsaunimodularmatri Uhav ing , b2, .. . , bn

    UA = A hasdninthe(n, mposit ion, w here

    ra in. B ysubtractingapropermultipleof the lastrow

    w s, amatri A 1isobta inedw hose lastco lumn

    hemaindiagona l.

    th c o lu m n ei t he r e ve r y el e me n t of t h e fi r st n 1

    ationof thef irstn 1row sanon-zeroe lement

    i , n m p os i ti o n. e t d n- 1 b e a g. c .d . o f

    , n -l . n - l ,n -l a nd l et

    + ^ n - l n -l ,n -l = < ^ n - l

    e r: M .- B . p re uB . A k a d . W i ss . 18 6 pp . 59 7 1 2.

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    n t eg r al M a tr i c es .

    1hasO' sabovethemaindiagona linthe last

    1, n mposit ion, andeachelementabove

    sothatthesecanbemadee ualto0byelementary

    essiscontinueduntilamatri isobtained

    bovethemaindiagona l.

    e inanyprescribedsystemofnon-associates,

    multiplyitby aunit.Thisis accomplished

    mationofthesecondtype.

    leof the( 1mthrow fromthe - th

    nbemadeto lie inanyprescribedresiduesystemmodulo

    yelementcanbereducedmodulothediagonal

    nderstoodthata= bmodO ifandonly if

    = j = 0, thenormalformofH ermiteisuni ue.

    n= ,buttheprocess isgeneral. uppose

    andB

    nd = ( lrs)

    = 0 , ^ 2 3 = 2 3 a 33 = 0 .

    0 , = j = 0 a n d l 1 3 = = 0 . i m il a rl y e ve r y el e me n t

    gona lis0.

    f^ , Z u, l22, ^ 33area llunitso f5p. Then

    dsincea iiandbubelongtothesamesystemofnon-asso-

    22 + 3 2

    systemmoduloa22,l32= 0.

    s = .

    non-singularmatri w hosee lementsare

    associateofamatri whosediagonalelements

    0 f o r r < i , a n d 0 ^ a r i < a u f or r > i . T hi s

    aselementsinaeuclideanring ,thereduction

    omplishedbyelementarytransformations.

    e lementsin . ithereverye lementof the last

    ast onenon-zeroelementwithminimum

    ninterchangeofthe rowscanbeputinto

    fanndoesnotdiv idesomeain, set

    s(ann))

    in e a ng e w. M at h . V o l .4 1 ( 18 5 1) p p . 19 1 2 1 .

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    n t eg r al M a tr i c es .

    nsformationofthethirdtype,ain canbe

    rchangerowsifnecessarysothat theelement

    nisofminimumstathmandproceedas before.

    eeveryain.Theproofnow proceedsasin

    modularmatri withelementsinaeuclidean

    itenumberofelementarymatrices.

    yTheorem22. 3theree iste lementary

    C / = V ,

    aandreduced. inced(U )isaunito f , each

    saunito f , andmaybeta entobe1. ince0

    temofresiduesmodulo1,U = .Then

    .. J E * ,

    tarymatri .

    unimodularmatri w ithe lementsinaeuclidean

    mberofunitsis aproductofa finitenumber

    iteset.

    lintegersby ronec er1.

    modularmatri withelementsinaeuclidean

    cesof thetypes

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    n t eg r al M a tr i c es .

    alintegralelementsandofdeterminant1 is

    namely

    sors. fthreematriceswithelements

    are inthere lationA = C D, thenDisca lled

    dA isca lleda le f tmultipleofD. A greatestcom-

    )Dof tw omatricesA andB isacommon

    multipleofeverycommonright divisorofA

    onlef tmultiple(l. c. l. m. )o f tw omatricesA andB

    hich isaright divisorofeverycommon

    .

    rofmatricesA andB withelementsin%

    ssible intheform

    ^

    roofo fTheorem22.1, aunimodularmatri U

    uchthatthe g.c.d.oftheelementsofthe

    nthe(n, n)-posit ioninUF. Thenelementary

    eto0everyelementof thiscolumnbelowann.

    uedto obtainane uation

    sunimodular.Thus

    D

    ghtdiv isoro fA andB isarightdivisoro fD.

    , theree istsamatri = X 1w ithe lementsin

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    oc i at e d n t eg r al M a tr i ce s .

    rofnon-singularmatricesA andB with

    . c. l. m. Muni ueuptoaunit le ftfactor.

    nB = 0

    fore

    ofA andB . fM1isanotherc. l. m. the ir

    Ml

    tsac. l.m . M2suchthatM= H M2. uppose

    .

    ,-X MB = H L B ,

    enon-singular,

    = H L .

    2 + . ^ 22 ^ 22 = H [ K Y 1 2 Y 2 i , so H i s a ui ut ma tr i ,

    fA f1. 1

    denoteann- thordermatri w ithe lementsina

    F oreverye lementmof theree istmatricesQ

    1) A = m Q o r e l s e (2 ) A = m Q + R w h er e

    mn ).

    he le ftbyaunimodularmatri , itcanbe

    rmalform. DetermineQ = ( r, ) , R = (rrs)such

    r i ,

    s ( m )f or > / , wh il e 0 < s (r if ) ^ s ( m) f or ' = ' .

    ) = * ( ) ,

    r M .. . rn n = s ( r l1 ) s (r 22 ) .. . s( rn ) < s (m ) n = s (m n) ,

    andeveryothere lementofR is0, i = m

    andsomeelementofR be low themaindiagonal

    otheoremsaredueinessenceto . C ahen: Th^orie

    aris1914, andintheformherepresentedtoA . C hate let:

    is1924.

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    n t eg r al M a tr i c es .

    ainform(2). etthelastcolumnhavinga

    hemaindiagonalbethet-th, andletr ibe

    hatcolumn. A ddrow torow i. Then

    1 wh er es d (R j ) < s (m n) .

    , t he nA = m U Q 1 + U R 1 w he re s d (U R j \ < s m n) .

    ndB arematriceswithelementsina proper

    d ( B ) = = 0 , t he r e e i s t m a tr i ce s Q a n d C s u ch

    a n d ei th er C = 0 o r el se 0 < s d (C ) < s d (B ) .

    istmatricesQ andR suchthat

    ,b = d B ) ,

    e 0 < s d (R ) < s ( bn ). f R = 0 , A = Q B a n d

    = 0 . f + R = A B A - bQ = A B A - Q B B A

    = C B A . T he n

    B A ,

    s d(C ) s d(B A ) = s i(C ) s^ " - 1 = s d(C ) s(ft) " - 1.

    ) = s i (B ) .

    ereprovedforrationalintegersby .G.du

    dedby thismeanstoestablishthee istenceof

    . e t bea linearformmodulo forder

    ing91. Thatis, consistso fa llnumbersof the

    an n .

    dependentlyover9 , andthee sare linearly

    to R . Thee sareca lledabasiso f .

    foranyotherset

    > % , ( ' , /= 1 .2 ,. .. , )

    odularw ithe lementsin9 isa lsoabasisfor ;

    onofthee sisa linearcombinationofthe

    onversely,everytwobasesofalinearformmodul

    sformation.Thefollowingdiscussionisrelative

    . ., enof .

    ar f o rm s u bm od u l of o r de r n o f , 2 a nd l e t h a ve

    n. Then

    ' . / = 1. 2, .. ., n)

    j schr. naturforsch. Ges. Z urichV o l. 51(190 )pp. 55

    lidealring, everysubmodulo f2isa linearformmodul.

    eneA lgebraV o l. I p. 121.

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    n t eg r al M a tr i c es .

    on-singularmatri w ithe lementsin9 . We

    G1isassociatedwiththebasisA , , X 2, . . ,

    rmatri G1determinesinthisw ayabasis

    f 2.

    , f it , . . ., f in isa linearformsubmodulo forder

    r y nu m be r o f 2 i s i n fi , a n d

    g k e .

    dwiththebasisfa, fi2,finof 2isC G1,

    armatri w ithe lementsin9 . Thisproves

    contains 2ifandonly ifG1is arightdivisor

    uls x and 2aree ua lif andonly if

    C 2 G 2, t h en C 1 C 2 = . s o th a t C 1 a n d C 2

    tri G1correspondstothemodulQ1 (G1 iC x ),

    sdeterminedonlyupto aunitleftfactor.

    rincipalidealringTheset ofnumbers

    1and 2constituteamodul ica lledthe

    dul(orlogicalproduct)ofthe twomoduls !

    sobedef inedasthatsubmodulo f21and 2w hich

    ubmodulo f 1and 2.

    tainedineither 1or 2orboth,to-

    differences,constitutesa modul2mcalled

    modul(orlogica lsum)of 1and 2. tmayalso

    conta ining 1and 2w hichisconta inedin

    1and 2.

    1,G2~ 2,Gd^ 2d,Gm~ m.ThenGd

    ,andGmis thel.c.l.m.ofG1andG2.

    of theg. c. r. d. andl. c. l. m . foreachisdetermined

    samelatitudeofdefinitionas thatofGd

    directlyfromTheorem24.1.

    swithrationalintegralelementsto the

    gepartduetoA . C hate let1. Hisw or is

    s, econssurla th^ oriedesnombres, Paris

    nsfinis,Paris1924.

    aringw ithunite lement, andlet bea linear

    9 whichisalsoa ring,andwhoseelements

    seof9 . A ninstanceofsuchasystemisadomain

    ociativealgebrainthesenseofDic son2.

    ,A n n . fi c ol e n or m . l l V o l . 2 8 (1 9 11 ) p p. 1 0 5 2 0 2

    ParisV o l. 154(1912)p. 502.

    lgebrenundihreZ ahlentheorie , p. 154. Z urich1927.

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    n t eg r al M a tr i c es .

    nstantsofmultiplicationof beci lc, anddef ine

    whichisclosedundermultiplicationon.theleft

    a lleda le f t ideal1. im ilarly theremaybedefined

    deals.

    of is aleftidealif andonlyifits cor-

    tisfiestheconditions

    1 , 2 , .. ., n )

    sw ithe lementsin9 .

    , . .. , X n constituteabasisfora le f t idea l% w here

    5 i s o f th e f or m

    k i gi e ,

    iso f theform

    ev e ry s l a nd i , t he r e e i s t nu m be r s dr o f 9 s u ch

    i c l h eh = d rg rt et .

    early independent,

    d rg rh .

    s t va l ue s d p r o f d r wh e n sl = d l p an d i 8 i .

    ~ 2 ,d pt rg rh ,

    d pr , ). ( P = 1 , 2 , .. . , )

    onissuf f icient. etdp randg j benumbers

    veconditions.Define

    ^ k iX iisevidentlya modul. etsbeany number

    r er = 2 i ( du, X s

    chisthereforealeftideal2.

    rrespondencebetweenidealsinanalgebraic

    aionalintegra le lements. fX l, X t, . . . , . H

    oerneA lgebraV o l. p. 53.

    rans. A mer. Math. oc. V o l. 31(1929)pp. 71 90.

    co lenorm. llV o l. 28(1911)pp. 105-202.

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    i n a n d = l l , X 2 , . . ., X n i s a d ia g on a l

    anecessaryandsuf ficientconditionthatA E A 1

    artf romadiagonalmatri asafactor, corre-

    l.

    principa lidealring f tw o lef t idea ls^ i

    basesA 1, . . . , X nandf il, . . ., f inrespective ly , theset

    isev identlyamodul. ince isaprincipa l

    mmodul. t isreadily seentobeclosedunder

    yanumberof , so it isa le f t ideal. The

    heproductofthe ideals3iand% 2inthatorder.

    rrespondencebetweenmatricesand uad-

    tanceofthecorrespondenceofthis paragraph,

    orrespondingtotheidealproduct thesecond

    roductofthematricescorrespondingto the

    morphismofidealmultiplicationwith com-

    rms.

    ngtotheproductofthe twoleftideals31

    thematrices

    n)

    Q2, andX 1, A 2, . .. , X n isabasiso f v

    renumbersofana lgebraicf ie ldofordern, aminimal

    )isreadilydeterminedfromits associated

    g.c. r. d. o f

    c ) .3

    r ic e s. e t A = P B Q , w h er e e ac h m at r i h a s

    dea lring J J . ThenA isamultipleofB .

    isamultipleof B ,theg.c.d.dtof thei-rowed

    dividestheg.c.d. dlofthei-rowedminordeter-

    romTheorem7.9.

    withelementsin aree uivalent A = B )

    dularmatricesUandV suchthatA = UB V .

    c o le p o ly t ec h n. C a h . 4 7 ( 18 8 0) p p . 17 7 2 4 5.

    . C . MacDuf fee: B ull. A mer. Math. oc. V o l. 37

    a t h. A n n . V o l . 10 5 ( 19 3 1) p p . 6 3 6 6 5 .

    e a ng e w. M a th . V o l . 1 14 ( 1 89 4 ) pp . 1 09 1 1 5.

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    nceisdeterminative,refle ive,symmetricand

    22. )Thepresentchapterhastodow iththoseproperties

    iantunderthis relationship.

    = B , everyg. c. d. dto f the i- row edminordeter-

    tedwitheveryg.c.d.d ofthei-rowedminordeter-

    ontherow sofamatri a redefinedasin 22,

    bymultiplyingthematri ontheleftby a

    ementaryoperationsonthecolumnsaredefined

    achbeingaccomplishedbymultiplyingthe

    unimodularmatri . The inverseofane lemen-

    ntaryoperationofthe sametype.

    matri A ofran withelementsin^ ise uiv-

    A x , ht, . . ., he , 0, .. . , 0 w hereA i1. 2

    alled mith snormalform.

    therow sandco lumnscanbeshif tedbyelementary

    eminordeterminantoforder intheupper

    0. ThenasintheproofofTheorem22. 1, thee lement

    anbemade= j = 0 andag. c.d. o f thee lementsof

    entsofthe firstcolumnbelowthefirstrow

    sbyelementary transformationsontherow s. f

    ndsinthe (1, mpositiondivideseveryother

    theseothere lementscana llbemadeO' sby

    onsonthecolumnssoasnotto disturbthe

    f theyarenota lldiv isibleby thise lementa11,

    heg.c.d.oftheelementsofthe firstrow,

    ewerprime factorsthanan.Theprocess

    ementinthe(1, mpositionisobtainedwhich

    ntofthefirst rowandeveryotherelement

    eeverynumberof% isfactorable intoaf inite

    geis reachedinafinite numberofsteps3.

    stn 1row sandcolumns, thenw iththe

    ndco lumnsetc., A canbereducedtoane uiva lent

    , 4 = 0 .

    elementofMw erenot0, itcouldbeshif tedinto

    posit ion, andA w ouldhaveanon-vanishingminor

    i.

    P hi l os . M ag . V o l . 1 (1 8 51 ) p p. 1 1 9 1 4 0.

    Ph il os . Tr an s. R o y . o c. o nd on V o l . 1 I (1 8 1 1 8 2 )

    erneA lgebraV o l. I p. 124.

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    umn3, . . . , co lumn toco lumn1, Dis

    rem22. 1, there isaunimodularmatri Uw hich,

    cesh1bytheg.c. d.ofhl,...,he.Thenew

    mentahomogeneouslinearcombinationof

    isdivisiblebythe newh1.A gain

    m hl, A 2, , A J w herenow h1divides

    tlhi+ 1, = 1, 2, . .. , (> 1.

    w ithe lementsinaring ' , w ithunit

    zero,in whichbothleftandright division

    hatis,astathm isdefinedforeverynumber

    , andforeverypa iro fnumbersaandb, b4= 0, there

    , r, r , s uc h th at

    r s( r) < s ( ) ,

    o r s( / )< s ( ) .

    ' iscommutative , it isaeuclideanprincipa lidea lring( .

    ' i s p ro p er .

    mationisoneoffivetypes:

    mentsofanyrowofthe productsofany

    thecorrespondinge lementsofanotherrow, be ing

    mentsofanycolumnoftheproducts of

    by thecorrespondinge lementsofanotherco lumn,

    tfactor.

    owsor oftwocolums.

    meunitfactorbeforeeachelementofany row.

    meunitfactoraftereachelementof any

    yoperationscanbeeffectedby multiplying

    ontheleftor ontherightby acertainelementary

    lementarymatricesisca lledaunitmatri , in

    nceptofdeterminantis notdefinedfor

    anon-commutativering.

    1hasprovedthatifA hase lementsin ' ,

    esPandQ suchthat

    , 0 ,. . .. 0 ,

    M . : . r e in e a ng e w. M at h . V o l . 1 7 ( 1 93 1 ) pp . 1 29 1 4 1.

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    r an o f A , a n d i f ( i s p ro p er , i s b ot h a r ig h t

    1

    properhadbeengivenessentiallyby . .Dic -

    result ingdiagona lmatricesarefactorable intoprime

    art fromunitfactors,thesameis truefor

    sin@' w hichareof ran n.

    ndelementarydivisors. etA beamatri

    palidea lring , andlet

    ,0

    lform(Theorem2 . 2). thasbeenseen(Theorem

    of the - rowedminordeterminantsofA isas-

    o f the - rowedminordeterminantsofD.

    di= h1h2...hiofthei-rowedminor

    destheg. c. d. di+ 1= h^ h^ . . . hi+1 of the(i+ 1m

    sofA .

    ,h2= d2 dl,h3= d d^ , arecalledthein-

    eyare invariantsunderthere lationofe uiv -

    duptoa unitfactor.

    everye lementne ither0noraunitcanbe

    ceptforunitfactors)intoaproductofpow ers

    , p h .

    ponentsofeachprimefactorformase uence

    . .. e u. ( 1= 1 , 2, . .. , )

    f asarenotunitsareca lledthee lementary

    strass . Theyaredef ineduptoaunitfactor.

    resimpleifeach isaprime4.

    B ifandonlyif A andB havethesameelementary

    .

    sameinvariantfactors, theycanbereduced

    andhencearee uiva lent. f theyaree ui-

    einvariantfactors,fortheseare invariants.

    minetheelementarydivisorsuni uely,and

    ricesA andB withelementsinacommutative

    lentifandonly if theyhavethesameran .

    rden: 1. c.

    lgebrasandtheirA rithmetics. Univ . o fC hicagoPress

    d er n e A l g eb r a V o l . p . 5 .

    - B . p r eu B . A k a d . W i s s . 18 7 4.

    mati . MacDuf fee. 4

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    mentofge cept0isaunit, andanormal

    maybechosenw herethenumberof l sis

    divisorsisoneof theoldestandmost

    anchesofmatrictheory.Theliteratureis so

    erisre ferredtoP . Muth sTheorieundA n-

    tarteiler1fortheearlypapers.Thetheorywas

    rass2forthepolynomialdomainofthecomple

    mith3andG. F robenius4formatricesw ithrational

    Frobenius5formatriceswithelementsin

    latergavearationaltreatmentofthe

    edthatifA andB haverationalintegra le lements,

    dMthe irl.c. l. m. , thenMA 1andMB 1

    meinvariantfactorsasB DlandA D1.

    r i . e t A b e a m at r i o f r an w i th

    a lringB yTheorem2 . 2, A isaproduct

    onalmatri

    . .. . 0 .

    ducto fmatricesof thetype

    actorofhi,and adiagonalmatri

    ran . Thematrices 1, . . . , pi,. . . , i have

    rethereforeirreducible8.

    thefo llow ingdecomposit ionforaunimodular

    af ie ldforthecase 4= 0:

    onw hen = 0.

    edthefactorizationofamatri intoe lementary

    - B . p r eu B . A k a d . W i s s . 18 8 p p . 31 0 3 3 8.

    P ro c . o n do n Ma t h. o c . V o l .4 ( 1 87 3 ) pp . 2 3 - 2 53 .

    eangew . Math. V o l. 8 (1879)pp. 14 208.

    r e in e a ng e w. M a th . V o l . 88 ( 1 88 0 ) pp . 9 1 1 .

    p r eu B . A k a d . W i ss . 1 89 4 p p. 3 1 4 4 .

    . A cad. ci. , ParisV o l. 177(1923)pp. 729-731.

    j schr. naturforsch. Ges. Z urichV o l. 51(190 )pp. 55

    . -B . p r eu B . A k a d. W i ss . 18 89 p p. 4 79 5 05 .

    o u v. A n n . M a th . l l V o l . 1 5 ( 18 9 ) p p . 34 5 -3 5 .

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    thateverymatri isaproductofe lementary

    i ( ) isobta inedby replacingthe0inrow i

    en t it y ma t ri b y . k ( ) i s o bt a in e d by r e pl a ci n g

    m n o f t he i d en t it y m at r i b y . " i s t he

    rowscycliclypermuted.

    everysecondorderintegralmatri isa

    nimportantinstanceofaprincipal ideal

    main (A )o fa llpo lynomialsin w ithcoef f icients

    Theelementsof% (e cept0)aretheunits

    ) iseuclidean, forifaandb= j = 0aretw onumbers

    sttw oothernumbers andrsuchthat

    eriso f low erdegree inX than . f is

    , thecomple f ie ld), theprimesin^ J (A )are

    .

    s0 + a rs lX + + a rs l ) w it h el em en ts i n

    omia lin ,

    o )+ (O r .i )A + + ( ar s ) X 1 ,

    triceswithelementsinThematri A

    4 = 0 . t i s p r op e r if i t i s of d e gr e e a n d

    ndB arematriceswithelementsin^ J (A ),and

    , thentheree istmatricesQ andR (Q 1and

    R , A = Q 1 B + R l ,

    1 = 0 ) o r el s e R ( R j ) i s o f de g re e < l .

    .. + A 0 , B = B { X l + . .. + B 0 ,l < k .

    0 , t he e u at io n B l X = A k h as a s ol ut io n X = C * - .

    k -iX k -lisof degree 1atmost.C ontinueasin

    a remainderisobtainedofdegree< Z .

    ndB areproperofdegrees and respectively,

    er e e i s ts a m at r i Q a n d tw o ma t ri c es R 1 a n d R 2 ,

    ectively,suchthat

    Q B + R , , P2 = A Q + R 2 , ^ < l ,r 2< k *

    hr. Ges. Wiss. Gottingen1909pp. 77 99.

    c c a d. n a z. i n ce i , R e n d. V V o l . 23 I ( 1 91 4 ) pp . 2 08 2 1 2.

    erneA lgebraV o l. p. 198.

    p r eu B . A k a d . W i ss . 1 91 0 p p. 3 1 5 .

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    2sothat

    P1 = Q ^ B + R 1 ,

    ree< / , andR 2is0 orofdegree

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    umof thematricesA l, A t, . . . , A k , andw ill

    .

    h A k .

    A ise uivalenttothematri

    5n - (X ) + + B . ( X ),

    X ) , . . ., h n (X ) i s t he m i th n o rm al f o rm o f X A ,

    r w hose invariantfactorsarea ll i sbutthe last

    i = = 1 , . .. , 1, f

    P n . , Q = Q n + Q n -l + . . .+ Q n - ,

    noftherows andcolumnsofPB Q gives

    maybechosentobe

    V , - 1 H

    educible insay

    .

    n t he f o rm X J , w h er e / i s th e o r da n f or m

    eeC oro lla ry15.1. )

    yclosedf ie ld , everyht(X ) be ingcomplete ly

    rmalformcorrespondingtoeachinvariant

    ordanformseachcorrespondingtoanelemen-

    A . B yashif t ingof therowsandco lumnsthese

    anyorder. ThusB (X ) canbechosen

    n ( l) + . .. + n { X ) ,

    e ordanformcorrespondingtoanelementary

    s e ,: ) .

    earetw otypesof invariantforthef ie ld ,

    haracterist ice uation, X ^ , . . ., X j , w hichmay

    tiona latheoriedessystemslinea ires. Z urich190 .

    ationtoA . H urw itz.

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    nts,andthee ponentseuoftheelementary

    edinvariantsofstructure1.The e ponents

    e 1

    e22, .. . ) ,. . . constitutethe egrecharacterist ic

    fmatrices. Twopairso fmatricesA l, A 2

    entsinacommutativefie ld% aresa idtobee ui-

    e isttwonon-singularmatricesPandQ

    that

    P B 2 Q .

    ndB 1arenon-singular,thefairsof matrices

    a r e e u i va l en t i f an d o nl y i f th e ma t ri c es A l X + A 2

    hepo lynomia ldomain (X ) havethesameinvariant

    sors)3.

    A , B 1 a+ B 2 = B . f A l = P B l Q an dA 2 = P B 2 Q ,

    Q foreveryX . nthedomainty (X ), PandQ

    determinantsarenon-zeronumbersof

    ariantfactorsof A andB coincide.

    B havethesameinvariantfactors, there

    dQ 1whosedeterminantsarenon-zeronumbers

    ay invo lveX , suchthatA = P lB Q 1. ince

    heree istbyTheorem29.3tw onon-singular

    lementsin% suchthat

    1 X + B 2 ) Q

    n c e A 1 = P B 1 Q a n d A 2 = P B 2 Q .

    erebothA landA 2aresingular, it ismore

    mmetriclinearcombinationA lX A 2f iw hose

    mialdomain^ (X ,fi)ofhomogeneouspoly-

    n^ (X , f i) isisomorphicw ith (a). The

    X + A 2f iw il lbecalledthe invariantfactors

    epairo fmatricesA ^ , A 2issa idtobeanon-

    A 2, u)isnotzero in^ (X , f i) .

    = A 1 f + A 2 , A 2 = A 1 r + A 2 s , wh er e f, , r, s

    a n d A 2 a r e in a n d if f s r = j = 0 , t h e n th e

    + A 2f iareobtainedf romthoseofA 1u+ A 2v

    X + s / n .

    n . Fa c . c i . Un i v. T o ul o us e V o l . 2 8 (1 9 14 ) p p. 1 8 4 .

    c c ad . n az . i n ce i , Me m . l l V o l . 1 9 ( 18 8 4) p p . 12 7 1 4 .

    r eu B . A k a d . W i ss . 1 8 8 p p . 31 0 3 3 8.

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    ninverse,definesanautomorphismof

    < J J ( , v )b y wh ic h A l X + A 2 f i o o /4 1m + A 2 v .

    ngularpairsofmatricesA l,A 2andB 1,B 2

    aree uivalentifandonly if theyhavethesame

    t, theyhavethesameinvariantfactors. This

    heorem30.1.

    ingularpair, theree istsanon-singularmatri

    . C h o os e r an d s in a ny w ay s o th at p s r = j = 0 ,

    + A 2s. Def ineB / , B 2 cogrediently . Thenby the

    e t he s a me i n va r ia n t fa c to r s as B 1 , B 2 , s i nc e A l , A 2

    actorsasB l, B 2. nthiscasethepa irsA ^ , A 2

    va lentbyTheorem30. 1. Thenthepa irsA uA 2

    va l en t .

    l isnon-singular, thepa irA l, A 2w ithe lements

    th e c an o ni c al p a ir , B w h e re

    + B n- ,

    matri o f the i- thinvariantfactoro fA l, A 2.

    1isnon-singularthepa irA l, A 2w ithe lements

    ie ld ise uivalenttothecanonica lpa ir ,

    + + n- ,

    tri o f the i- thinvariantfactoro fA l, A 2.

    valenceofsingularpairsofmatrices presents

    andP.Muth2treatedsingular pairsof

    h3treatedthegenera lcase. . . Dic son4

    airsare e uivalentbyrationaltransformations

    sameinvariantfactorsandthe sameminimal

    fnes. TurnbullandA it en5havean

    ngularcase.

    rethan onevariableisusuallynotfactorable

    eierstrasselementarydivisortheorydoes

    applicabletotheproblemof thee uivalence

    matrices. . antor genera lizedtheconcept

    eometricmethodstohandlethis problem.

    uivalenceofpairsofmatriceswas developed

    n7. F irstsupposethatl1, .. . , A aretheroots

    V o l. 38(1891)pp. 24 49.

    o l. 42(1893)pp. 257-272.

    nwendungender lementarteiler.Teubner1899.

    a ns . A m e r . Ma t h. o c . V o l .2 9 ( 19 2 7) p p . 23 9 2 5 3.

    : C anonicalmatrices, C hap. X . Glasgow 1932.

    : . -B . B a ye r. A k a d. W i ss . V o l. 98 ( 18 97 ) pp . 3 7 3 81 .

    G . D .: T r an s . A m e r. M at h . o c . V o l . 2 ( 1 92 4 ) pp . 4 51 4 7 8.

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    \ = 0 a n d ar e a ll d i st i nc t . e t A = ( a r, ) ,B = ( b r l) . T he r e

    , . . . , n ), (yn, .. . , y ln), nooneofwhichconsists

    = 0 , (i , = i , 2, .. ., n)

    0. ( , / = 1 ,2 , )

    lizedsothat Z i,iy ibi X i = 1. ince

    = h 2 yn bi j k = h 21 yn bu a ,

    ,

    0 , > - < > ^ t = 0.

    #re)and = (yrs) areorthogonalrelativetoA andB .

    = l l, l2 ,. .. ,X n .

    X B \ = 0 a r e no t a ll d i st i nc t , va r io u s

    ismultiple , thenumberof linearly independentpo les

    e ua ltothemultiplicity . nthiscasethe

    ore.Thecasewhenthereare fewerlinearly

    emultiplicitypis calledtheirregularcase.

    uations

    ^ ? ( h = 2, .. ., p)

    so fX and . fX k isarooto fmultiplicity3.

    mberoflinearlyindependentpolesisi, the

    X B is

    ormations. fPA Q = A , thee lementsof

    mmutativefieldg, thematricesPandQ

    ctransformationofA withrespecttothe

    .

    4= 0andMis anarbitrarymatri suchthat

    0 t h en

    M ) Q = ( A + M )1 (A - M )

    nsformationofA .Therearenoothers forwhich

    O . 1

    Tr a ns . R o y . o c . o n do n V o l . 14 8 ( 18 5 ) p p . 39 4 .

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    = ( - A l M) ( + A l M) ,

    ( A - M ) A 1 ( A + M ).

    o feachmemberitfo llow sthat

    )1 = ( A + M A { A - M )1 ,

    ( A + M ( A - M) = A .

    e ist, botharenon-singular, andtheydefine

    def iningPandQ y ie lds, respective ly ,

    , M = A ( - Q )( Q + f .

    ( P+ ) A ( - Q ),

    ree ua l. HenceforeveryPandQ such

    ( P + ) 1 a nd Q + ) 1 e i s t, t h er e i s an M i n

    maybedefinedasin thestatementofthe

    andQ + / benon-singularisaserious

    asilyavoided.

    P A Q = B , d ( Q ) 4 = 0 , t he n f (P ) A f ( Q 1 ) 1 = B ,

    ctionsuchthatf(Q 1)isnon-singular.H e

    ryand sufficientconditioninorderthatP

    nsforminganon-singularmatri intoitselfis

    dertheelementarydiv isorsof1 Pand

    tcorrespondinge lementarydivisorsareof thesamedegree

    aluesof A .

    tsinaprincipa lidea lring. fA = PTB P

    lementsinaprincipal idealringandif P

    congruentw ithB , w rittenA = B . C ongruence

    a lence, andisdeterminative, re f le ive , sym-

    f . 22. )

    x ^^ ofmatri B betransformedbycogre-

    matri P intoaformofmatri A , then

    epurposeof thew ritertopresentthesub ectas

    mthe notionofbilinearform,butthe

    yin translatingtheresultsintotheno-

    sodesires.ThusTheorem34.1statesthat

    ng e w. M a th . V o l . 4 ( 1 87 8 ) pp . 1 3 .

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  • 7/28/2019 Thoery of Matrices Mac Duffee

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    sin J 5(Theorem21.1). ThenPTQP isof the

    property that 12= j = 0anddiv ideseveryother

    yelementarytransformationstheseother

    s. Theprocessmaybecontinueduntilamatri

    eryothere lementof , oranothercongruent

    can beobtainedinwhichtheelementin the

    rimefactorsthan 12. B yaddingrow 2,

    andthenaddingcolumnssimilarly,a new

    tainedwhosefirstrowconsistsof

    1 2 ^ 23 , ^ 13 = 2 3 ^ 34 , h n = - 1, n

    . ., & -1, n)isag.c. d. o f ( l12, . . ., l ln)andcon-

    arto f thisproof , acongruentmatri canbe

    butwiththeelementin the(1,2mposition

    n-1,n). Unless 12 k i^ l, if o revery i, thisg. c.d.

    orsthan 12.

    stepsamatri canbereachedin

    element.B yproceedingsimilarlywiththelast

    o lumns, amatri isobta inedinw hich

    g 1 , /,

    multipleof row 1torow , 23canbemade0.

    vencanbemade0insuccession. Thisprovesthe

    issingularifnisodd(Theorem8. ). et

    ersA ,,h1,h2,h2,. ..,h^ ,ofthecanonical

    antfactorsofQ .

    eterminantsare^ h ih ,... h .,where

    eroftheset1, 2,...,fi nointegerofwhich

    e. tisevidentthenthat theg.c.d.ofthe

    antsisdt hlh1h2h2h3. . . to ifactors. Thus

    , d d 2 = . h 2, , w h i c h pr o ve s t he t h eo r em 1.

    ew canonica lformisuni uee ceptthatthe

    byassociates.

    einvariants( 27).

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    ewmatriceswithelementsinarecongruent

    sameinvariantfactors.

    os ew matricesw ithe lementsinaree uivalent,

    ew matri the2i-thinvariantfactorise ua l

    .

    d.oftheminorsof thesameevenorderof

    er f ec t s u a re 3 .

    achotherconstitutea class.

    isbut afinitenumberofclassesof non-singular

    endeterminant.

    primesinaprincipa lidealringisuni ue

    ereis butafinitenumberof choicesforeach

    mmetricmatricesisby nomeansas

    matrices.Thistheoryoccursin theliterature

    w ith uadraticforms. There lationA PTB P

    isenste in4, w honotedthatifa uadraticform

    ormedbyatransformationofmatri P , thenew

    tri A .

    mmetricmatri ofran withelements

    iscongruentw ithamatri o f theform

    Q .

    ticalwith thatofthefirst partofthe

    ni ue,andindeedtheproblemof finding

    nonicalformisoneofe tremedif f iculty if it

    thasnotbeen attainedevenfortwo-rowed

    arerationalintegers,aswillappearin thene t

    ntegralelements.Thistopic,which

    ortantchapterin thetheoryofnumbers,

    ere. C ompletereferencesuptothedate

    eninarticlesby . T . V ahlen , and

    ngew . Math. V o l. 8 (1879)pp. 14 208.

    nius:1.c.

    r e in e a ng e w. M at h . V o l .3 5 ( 18 4 7) p p . 11 7 1 3 .

    z y l . m at h . W i ss . V o l . 2 C 2 ( 1 9 04 ) p p. 5 8 2 6 3 8 .

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    treatisesbyP. B achmann2andDic son3cover

    hy .

    altheoremwasstatedbyC .H ermite4and

    ouff5.

    ta finitenumberofclassesofsymmetric

    gralelementsofgivennon-zerodeterminant.

    )

    clusionhere.

    ivedef inite . f

    a ,

    a , t he m at r i A i s c al l ed r e du c ed . v e ry p o si t iv e

    oforder2is congruentwithoneandonly

    ca lledindef inite. f / isthatrooto f

    0

    eradical,ands istheotherroot,then A is

    s > 1 , f s < 0 . H e r e a ga i n th e re i s a t le a st o n e

    s,and usuallymorethanone,butnever

    yamethodofGauss thesecanbear-

    edforms sothateachchaincorresponds

    ttoindicate thegeneralsituation.C an-

    finedinvariouswaysso thateveryclass

    stonce andatmosta finitenumberoftimes.

    uecanonicalformhasbeenattainedon