Helloooooooooooooooooooooooooo Dima !!!
Yesterday I went to walk around the Calanques near the University of
Marseille, and it did me good ! I am now wandering homeless in Paris and
that's another story :-P
Buttttttttt the thing is that I thought a bit about our conversation here
and I think I understand our misunderstanding better. That's only because
Thomas Connor mad me read something about Incidence Geometry a long time
ago :-D
So for a start, it took me some time to accept that you see nothing wrong
-- in a group where all elements of the domain are integers 1, .... , n --
with wanting to compute the orbit of (1, {1,2}), when of course {1,2} is
not a member of the domain. Of course, now if {1,2} *IS* a member of the
domain then you do not see how to interpret (1, {1,2}) given as input and
everything becomes dark, sad, evil and totally non-beautiful at all.
SO. First, the thing is that GAP apparently does not know how to do that
either. It accepts only a list of things which are "at the same level",
that is a tuple (element, element) and not a tuple (element, pair of
elements). That's what I need myself so I don't complain if GAP does not
know better and I would be prettyyyyyy glad if this feature could be
exposed for a start. And for this kind of input we know all we have to with
the value of "action" exactly as GAP already does it.
Then I agree that it would be great to have a way to say g.orbit( (1,
{1,2}) ) and have Sage do all the job. Well, at this level I have no idea
how it should be actualy implemented (I'm interested in the ways but so
ignorant of such things that I probably will not be of much help), but I am
not scared anymore of the interpretation of input : as Volker said earlier
(which I had not noticed then) we could just write some code at the
beginning of "orbit" which checks that input can never be misnterpreted
(and cache the result of this computation) so that we can be proud of what
we return. And if input can be misinterpreted we would just scream in panic
and raise an IAmClueless error saying so. Which will not happen in your
applications, which will not happen in mine either, and which will never
happen whenever "action" is defined anyway
Now what you think of it ? That we implement this method for a given value
of "action", and think hard of how to extend GAP's features in Sage ?
Have fuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuun ! It's grey in Paris
and everything is expensive, but I have found a couch somewhere for the
next two weeks ;-)
Nathann
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