#20445: Iteration through Coxeter groups
---------------------------------+------------------------
Reporter: stumpc5 | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-7.2
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by stumpc5):
{{{
###########################################################################
#
# N.B. a difference with older versions of Chevie is that IsLeftDescending
and
# FirstLeftDescending return an index in the list of generators,
not a
# reflectionName, for efficiency. LeftDescentSet still returns names
of
# reflections.
#
###########################################################################
## generic reduction of FirstLeftDescending to IsLeftDescending
## in practical implementations of Coxeter groups this routine can often
## be overriden by a more efficient one.
AbsCoxOps.FirstLeftDescending:=function(W, x)local i,ILD;
ILD:=W.operations.IsLeftDescending; # avoid dispatching overhead
for i in W.generatingReflections do if ILD(W,x,i) then return i; fi; od;
return false;
end;
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/20445#comment:2>
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