GroupTheory
Character
construct a finite group character from a character table
Calling Sequence
Parameters
Description
Methods
Examples
Compatibility
Character( ct, k )
ct
-
character table
k
positive integer
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.
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
with⁡GroupTheory:
G ≔ Alt⁡4
AlternatingGroup⁡4
ct ≔ CharacterTable⁡G
GroupTheory:-CharacterTable⁡module...end module
Retrieve the fourth character (i.e., the last row) from the character table.
Character⁡ct,4
GroupTheory:-Character⁡module...end module,4
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
`.`⁡c4,c4
1
`.`⁡c3,c4
0
Since the irreducible characters form an orthonormal basis, the following produces an identity matrix.
Matrix⁡4,4,i,j→`.`⁡c||i,c||j
1000010000100001
K ≔ Kernel⁡c3
GroupTheory:-PermutationGroup⁡module...end module,module...end module,module...end module,degree=4
IsNormal⁡K,G
true
GetValues⁡c3
1,1,−12+I⁢32,−12−I⁢32
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
map⁡Indicator,c1D4,c2D4,c3D4,c4D4,c5D4
1,1,1,1,1
The GroupTheory[Character] command was introduced in Maple 2017.
For more information on Maple 2017 changes, see Updates in Maple 2017.
See Also
GroupTheory[AlternatingGroup]
GroupTheory[CharacterTable]
GroupTheory[DihedralGroup]
GroupTheory[QuaternionGroup]
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