SiftedAgWord( U, g )
SiftedAgWord tries to sift an ag word g, which must be an element of
the parent group of an ag group U, through an induced generating system
SiftedAgWord returns the remainder of this shifting process.
The identity is returned if and only if g is an element of U.
Let u_1, ..., u_m be an induced generating system of U. If there
exists an u_i such that u_i and g have the same depth, then g is
reduced with u_i using
ReducedAgWord (see ReducedAgWord). The
process is repeated until no u_i can be found or the g is reduced to
Factor Groups of Ag Groups for details.
SiftedAgGroup adds a record component
U.shiftInfo to the
ag group record of U. This entry is used by subsequent calls with the
same ag group in order to speed up computation. If you ever change the
U.igs by hand, not using
Normalize, you must unbind
U.shiftInfo, otherwise all following results of
gap> s3 := Subgroup( s4, [ a, b ] ); Subgroup( s4, [ a, b ] ) gap> SiftedAgWord( s3, a * b^2 * c ); c
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