On Sun, Jan 09, 2011 at 11:47:35PM -0800, Simon King wrote:
> On 9 Jan., 18:10, Dima Pasechnik <[email protected]> wrote:
> > On Jan 8, 1:54 pm, Simon King <[email protected]> wrote:
> > ...
> > IMHO there should be several levels of equivalence, depending upon the
> > nature of morphism to be applied
> > (1) trivial morphism
> > (1 1/2) a permutation of the basis
> > (2) orthogonal
> > (3) Hermitian
> > ....
> > (coarsest) arbitrary (i.e. the characters are the same for both
> > representations)
> >
> > I suppose the design should allow for user-defined/extendible
> > equivalences.
>
> OK, but as a short-term solution, I'd prefer to re-implement the
> current way of comparison so that it is essentially the same to what
> happens now, but is invariant against adding attributes (so that the
> bug in the example above won't occur).
Semantically, I would choose to have equality mean (1), and leave the
others to specific method(s) like "is_isomorphic". This turns out to
coincide with what Simon is implementing :-)
> By the way, I've hit that bug when I worked on speeding up
> cached_method decorators. Namely, one part of the speed-up comes from
> using an additional attribute - and since the representations have
> some cached_method, the comparison broke. I just realize that I had
> forgotten to mention it on the ticket.
>
> It is #8611 and ready for review (if you care about making
> cached_method a lot faster).
I do!!!!!! I'll have a look. Thanks!
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <[email protected]>
http://Nicolas.Thiery.name/
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