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GroupTheory

  

Character

  

construct a finite group character from a character table

 

Calling Sequence

Parameters

Description

Methods

Examples

Compatibility

Calling Sequence

Character( ct, k )

Parameters

ct

-

character table

k

-

positive integer

Description

• 

The Character( ct, k ) command creates the kth character of the character table ct, which may be constructed by using the CharacterTable command from a finite group.

Methods

• 

Characters are implemented as Maple objects and support several object methods, outlined below.

Indicator( chi, k )

returns the kth higher indicator of the character chi

Indicator( chi )

returns the Frobenius-Schur indicator of the character chi

Kernel( chi )

returns the kernel of the character chi

chi1 . chi2

returns the inner product of characters chi1 and chi2

Examples

> 

with⁡GroupTheory:

> 

G≔Alt⁡4

G≔A4

(1)
> 

ct≔CharacterTable⁡G

ct≔C1a2a3a3b|C|1344X11111X211−12−I⁢32−12+I⁢32X311−12+I⁢32−12−I⁢32X43−100

(2)

Retrieve the fourth character (i.e., the last row) from the character table.

> 

Character⁡ct,4

character: 1a→3,2a→−1,3a→0,3b→0 for A4

(3)

The next statement assigns all the characters from the table.

> 

c1,c2,c3,c4≔op⁡map2⁡Character,ct,seq⁡1..4

c1,c2,c3,c4≔character: 1a→1,2a→1,3a→1,3b→1 for A4,character: 1a→1,2a→1,3a→−12−I⁢32,3b→−12+I⁢32 for A4,character: 1a→1,2a→1,3a→−12+I⁢32,3b→−12−I⁢32 for A4,character: 1a→3,2a→−1,3a→0,3b→0 for A4

(4)
> 

c4·c4

1

(5)
> 

c3·c4

0

(6)

Since the irreducible characters form an orthonormal basis, the following produces an identity matrix.

> 

Matrix⁡4,4,i,j↦c‖i·c‖j

1000010000100001

(7)
> 

K≔Kernel⁡c3

K≔1,42,3,1,23,4

(8)
> 

IsNormal⁡K,G

true

(9)
> 

GetValues⁡c3

1,1,−12+I⁢32,−12−I⁢32

(10)

Notice that, although the non-Abelian groups of order 8 have identical character tables, they are distinguished by the Frobenius-Schur indicator.

> 

ctQ≔CharacterTable⁡QuaternionGroup⁡:

> 

c1Q,c2Q,c3Q,c4Q,c5Q≔op⁡map2⁡Character,ctQ,seq⁡1..5:

> 

ctD4≔CharacterTable⁡DihedralGroup⁡4:

> 

c1D4,c2D4,c3D4,c4D4,c5D4≔op⁡map2⁡Character,ctD4,seq⁡1..5:

> 

map⁡Indicator,c1Q,c2Q,c3Q,c4Q,c5Q

1,1,1,1,−1

(11)
> 

map⁡Indicator,c1D4,c2D4,c3D4,c4D4,c5D4

1,1,1,1,1

(12)

Compatibility

• 

The GroupTheory[Character] command was introduced in Maple 2017.

• 

For more information on Maple 2017 changes, see Updates in Maple 2017.

See Also

GroupTheory

GroupTheory[AlternatingGroup]

GroupTheory[CharacterTable]

GroupTheory[DihedralGroup]

GroupTheory[QuaternionGroup]