ConsiderKernels( tbl, chars, prime_powermap, prime )
ConsiderKernels( tbl, chars, prime_powermap, prime, "quick" )
More about Maps and Parametrized Maps) that is an approximation of the prime-th powermap of the character table tbl:
For G a group with character table tbl, the kernel of each character in the list chars is a normal subgroup of G, so for every g in 'Kernel( <chi> )' we have g^{<prime>} in 'Kernel( <chi> )'.
Depending on the order of the factor group modulo Kernel( chi )
,
there are two further properties: If the order is relative prime to prime,
for each g notin 'Kernel( <chi> )' the prime-th power is not contained
in Kernel( chi )
; if the order is equal to prime, the prime-th powers
of all elements lie in Kernel( chi )
.
If "quick"
is specified, only those classes are considered for which
prime_powermap is ambiguous.
If Kernel( chi )
has an order not dividing tbl.order
for an element
chi of chars, or if no image is possible for a class,
false
is returned; otherwise ConsiderKernels
returns true
.
Note that chars must consist of ordinary characters, since the kernel of a virtual character is not defined.
# see example in "Congruences" gap> ConsiderKernels( t, t.irreducibles, pow, 2 ); pow; true [ 1, 1, 3, 4, 5, 2, 2, 8, 3, 4, 11, 12, [ 6, 7 ], 14, 9, 1, 1, 2, 2, 3, 4, 5, [ 6, 7, 18, 19 ], 8, 9, 9, [ 10, 21 ], 11, 12, 16, 16, [ 2, 16 ], [ 2, 16 ], 17, 17, [ 6, 18 ], [ 6, 18 ], [ 6, 7, 18, 19 ], [ 6, 7, 18, 19 ], 20, 20, [ 9, 20 ], [ 9, 20 ], 22, 22, 24, 24, [ 15, 25, 26 ], [ 15, 25, 26 ], 28, 28, 29, 29 ] # continued in "PowermapsAllowedBySymmetrisations"
ConsiderKernels
is used by Powermap Powermap
.
GAP 3.4.4