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Γραμμική Άλγεβρα ΙΙ Σελίδα 1 από 13 Μάθημα 7 ο ΘΕΩΡΗΜΑ CAYLEY-HAMILTON Θεωρία : Γραμμική Άλγεβρα: εδάφιο 6, σελ. 160 Ασκήσεις : 1, 2, 3, σελ. 162. Ελάχιστο πολυώνυμο πίνακα Έστω πίνακας . Από το θεώρημα Cayley-Hamilton συμπεραίνουμε A ν×ν ότι το σύνολο των πολυωνύμων p( ) λ , ώστε ( ) p A O = , δεν είναι κενό. Το πολυώνυμο ελαχίστου βαθμού (7.1) 1 1 1 () c c c κ κ− κ− µλ=λ + λ + + λ+ " 0 ώστε ( ) A O µ = , ονομάζεται ελάχιστο πολυώνυμο του πίνακα . A Παραδείγματα : 1. Αν , έχουμε ( ) diag , , , A I = α α α= α () A I O α = ⇒ µ λ =λ−α . 2. Αν , βρίσκουμε 1 2 2 0 3 4 0 2 3 A = I 2 A = και επειδή , θα είναι A ≠αI 2 () 1 µ λ =λ − . 3. Αν , έχουμε 1 2 2 2 1 2 2 2 1 B = I 2 4 5 B B = + και κατά συνέπεια, 2 () 4 5 µ λ =λ − λ− . 4. Ο αδύναμος πίνακας έχει ελάχιστο πολυώνυμο ( 2 A A = ) 2 () µ λ =λ −λ .

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  • 1 13

    7

    CAYLEY-HAMILTON

    : : 6, . 160

    : 1, 2, 3, . 162.

    . Cayley-Hamilton A p( ) , ( )p A O= , .

    (7.1) 11 1( ) c c c = + + + +" 0 ( )A O = , . A :

    1. , ( )diag , , ,A I= = ( )A I O = = .

    2. , 1 2 20 3 40 2 3

    A =

    I2A = , A I

    2( ) 1 = .

    3. , 1 2 22 1 22 2 1

    B =

    I2 4 5B B= + ,

    2( ) 4 5 = . 4. ( 2A A= ) 2( ) = .

  • 2 13

    5. ( )A O = . ( ) =

    7.1 ( ) A( ) , A ( ) ( ) .

    : ( ) ( )( ) ( ) ,

    ( ) ( ) ( ) ( ) = + . ( ) (( ) ( ) < )

    ( ) ( ) ( ) ( ) ( )A A A A A = + = O , , A ( ) .

    ( ) A , p( ) p( )A O= .

    7.2 . A

    : (7.1) ( ) A1

    1 1 0( ) d d d

    = + + + +" , ( )A O = .

    ( ) ( )11 1 1 1 0( ) ( ) ( ) c d c d c d = = + + + " 0

    ( ) ( ) ( )A A A = = O , , ( )( ) 1 = ( ) . A

    7.3 A

    . ( ) A

  • 3 13

    : 0 A0( ) ( ) ( ) c = + , c 0 .

    0( ) ( ) ( ) cA A I A I = + = O

    0( )( )cAA I I = .

    , , ( )0det 0A I = , . , 0 1= c 0c 0= .

    :

    A( ) ( ) ( )1 21 2( ) = "

    ( ) ( ) ( )1 21 2( ) = " , i i0 < . ( ) A n

    (. ), . i 1 = ( ) ( )

    7.4 A

    , ( ) A( )( ) ( )1 2( ) = " , .

    : ,

    10 10 0 1

    A =

    .

    , ( ) (2( ) 1 1 = + ) A

  • 4 13

    ( )( ) 2( ) 1 1 1 = + = . ,

    2

    1 20 1 0 00 0 1

    A I = =

    = .

    7.5 .

    : 1A PBP= ( ), ( )A B .

    1( ) ( )B BA P B P O = = ,

    7.1, ( )A ( )B . , : 1B P AP=

    1( ) ( )A AB P A P O = =

    ( )B ( )A . ( ) ( )A B = .

    7.5 ,

    .

    . 1 1 00 2 00 0 1

    A =

    2 0 00 2 20 0 1

    B =

    ,

    ( )( )( ) ( ) 1 2A B = = , ( ) (2( ) 1 2A ) =

    ( ) ( )2( ) 2 1B = . , A B .

    7.6 . A TA

    : ( ) ( ) ATA .

  • 5 13

    7.1 6.10, . 161.

    * * *

    7.2 ,

    Cayley-Hamilton

    , ,A B

    A OM

    O B = ,

    AN

    O B =

    .

    TT( ) ( )A A = = O [ ]TT( ) ( )A A O = = ( ) ( ) ( ) ( ) , ( ) ( ) = .

    7.7 A O

    EO B = E.K. .

    . A B

    : ( )E = E.K. . { }( ), ( ) ,A B ( ) ( ) p( )E A = ( ) ( )q( )E B =

    , ( )E = ( )E = . , k( ) ( ) (k( ) ( )E ) < k( )E = , { }k( ) diag k( ), k( ) ,E A = B k( ) k( )A B= = 7.1 ( )A ( )B . , k( ) ( )E E.K. . ( )A . ( )B

  • 6 13

    : , ( )A ( )B .

    A B M N

    ( ) ( ) ( )A B = , ( ) ( ) ( ) ( )det det det detI M I N I A I B = =

    . ( ) ( )M N = =O* * *

    7.3 1 13 1

    A = , . 2005A

    : ( ) ( ) 2det 4A I A = = , Cayley-Hamilton . , 2 4A = I ( )10022005 2 10024A A A= = A .

    , .

    ( ) 1diag 2, 2A P P= .

    ( )( )( )

    20042005 2004 2004 1

    1002 1002 1 1002 1 1002

    diag 2 , 2

    diag 4 , 4 4 4 .

    A A A P P A

    P P A PP A A

    = = = = =

    1

    * * *

    7.4 1 0

    1diag 0 1 , ,

    0 00 0

    J =

    ,

    . ( )J : ,

    . 7.7,

    ( )31( ) = ( 22 ( ) = ) )

    )( 23 ( ) =

    ( )J = E.K. . { } ( ) (3 21 2 3( ), ( ), ( ) = .

    * * *

  • 7 13

    7.5 3 3 A2 3 2A A I O + = .

    : A ( ) 2p 3 2 = + ,

    . :

    ( )(1= )2

    I

    ( ) A ( ) 1 A I = = , ( ) 2 2A = = ( ) ( )p = , ( 7.4) ,

    A

    1A PDP=( )diag 1, 1, 2D = ( )diag 1, 2, 2D =

    . P

    , A ( ) ( )p = ,

    A

    ( )diag , 2D I I = , + = .

    * * *

    7.6 1 0

    0 10 0

    A =

    , 1 0

    00 0

    B

    0 =

    ( )diag , , = ,

    , . ( ) ( ) : .

    ,

    ( 3( ) ( ) ( )A B = = = ))( )3( )A = ( 2( )B = ( ) = .

    , 7.5,

    .

    * * *

  • 8 13

    7.7 N

    5 3 24 2 0

    0 0 2A

    = ,

    1 00 10 0

    B =

    .

    : y A

    ( ) ( ) ( ) (25 3 2 24 2A

    I A = = = + )1 .

    A ( )( )2A I A I O , . ( ) ( )A A

    y ,

    B2

    1 0c cB B= + I2

    2 2

    2

    2 10 20 0

    B =

    (1.3) 1 = 0, .

    B

    .

    0c , c1

    O

    ( ) ( )3B = * * *

    7.8 , 2 4 3

    0 0 01 5 2

    A =

    593 152A A A + = .

    : ( ) ( )( )3 1 1A I A = = = + . ( ) 593 152 = + ( ) ( ) ( )0 1 1 0 = = = , ( )A ( ) . , Cayley-Hamilton

    ( ) 593 152A A A A O = + = .

    * * *

  • 9 13

    7.9 1 2 20 3 40 2 3

    A =

    .

    . ( ) . ( ) (3 102A I A I A I + )9I

    9

    . . 2005 20042 2A A A+ = + : . A

    ( ) ( ) ( )21 1A = + . ( ) ( ) ( ) ( )3 102 1 1 = +

    ( )A , ( ) ( ) ( )A = Cayley-Hamilton

    ( ) ( ) ( ) ( ) ( )3 10 92 AA I A I A I A A O + = = . . ( ) ( )( ) 21 1 = + = 1

    I

    , . A 2A =( ) ( )1002 10022005 2004 2 22 2A A A A A A+ = + = + 2I .

    * * *

    7.10 1 1 03 1 00 0 2

    A =

    .

    . 4 3 26 2 7A A A A I + + . . ; A

    . 1A 2A . A

    : . ( ) ( )( )2 3 22 4 2 4A I A = = = + 8 ( )( ) ( )4 3 26 2 7 1 2 1A + + = + + .

    Cayley-Hamilton 4 3 26 2 7 2A A A A I A I + + = .

    . ,

    ( ) ( ) ( ) ( )2det 2 2A I A = = +

  • 10 13

    ( ) ( )( )2 = + 2 ( ) ( ) ( )22 2 = + . ( ) ( )( )2 4A I= = +2 2 7.4, . A

    ,

    ,

    2 =

    ( ) ( )d 2 3 rank 2 3 1 2A I= = = . . ( )0 8A = 0

    O

    ,

    . ( Cayley-

    Hamilton)

    ( )3 1 2 31 8 det A = =A

    3 22 4 8A A A I + = 1A

    ( )1 21 2 48A A A = I . 2A ,

    ( ) ( ) ( )2 1 21 1 1 12 4 2 2 4 88 8 2 16A A I A A I A A I A = = + = 2 I .

    * * *

    7.11 ( )p ( ) .

    A ( )pB A=( ) ( )p

    .

    : ( ) ,

    ( )p ( ) ( )1 2q , q

    ( ) ( ) ( ) ( )1 2q p q + =1.

    ( ) ( ) ( ) ( ) ( ) ( ) ( )( )1 2 2q p q p q det pA A A A I A A I A + = = 0 .

  • 11 13

    , ( ) { }1 2, , ,A = , ( )( ) ( ) ( ){ }1p p , , pA = . B ,

    ( )( ) ( ) ( ) ( ) ( )1 2 idet p p p p 0 p 0A = " i 1 . , 2, ,= ( ) ( )p , .

    * * *

    7.12 5 2 22 2 42 4 2

    A =

    .

    . k\ kA I+ .

    . .

    . ( )1 1 318

    A A = I , 2 1 112 108

    A I = A I . ( )3 27 2A A= + : . A

    ( ) ( )( 23 6A I A = = + )I

    .

    , kA + { }k 3 k, 6 kA I+ = + + . k 3>. ( ) ( )( ) 23 6 3A = + = 18. , ( 7.4).

    ( )A A

    , ,

    6 =( ) ( )( )d 6 3 rank 6 3 1 2A I= = =

    . A

    . ( )0 108A = 0 ,

    A

    1A

    ( ) 2 3 18A A A A I O = =

    (1 1 318

    A A = )I . ( )2 11 1318 12 108A I A I = = 1 A .

  • 12 13

    Cayley-Hamilton 1A 2A

    2 .

    ,

    .

    A

    ( )( ) 2 3 =