On Apr 17, 4:29 am, Dan Drake <[EMAIL PROTECTED]> wrote:
> On Wed, 16 Apr 2008 at 09:22PM -0700, Mike Hansen wrote:
> > What do you want to do with posets?
Hmm, well for now I'd be happy with the ability to place an arbitrary
set of strings (or other Sage objects) into a total ordering, I guess,
that I could use one of the permutation group functionalities to spin
around ('A'>'B'>'C'>'D' to 'D'>'C'>'B'>'A' via Z_2, for instance),
though eventually I think that I would want full poset functionality
too. The point is that I'm not sure how to tell elements that they
are greater than each other without defining a new class with _cmp_ or
something, which would be the opposite of my goal of being able to
dynamically assign an ordering to an arbitrary set.
Unfortunately at this point neither I nor my students are in a
position to be able to implement something like this, which is why I
hope that at least total orderings are possible and then maybe I can
use that to do what I want to do (which is, as stated above, to mess
with said orderings in all sorts of ways).
>
> I'd like posets too. What I want is to have a bunch of objects, and
> define a poset with them...I want to provide a "<" function and then
> have the poset code list all elements <= a given element, in an
> interval, get a list of minimal elements, and so on.
>
> Dan
>
These sound good too. Thanks for any other thoughts on where these
things might live in code for me to peruse should I indeed at least
try to implement at least a very poorly coded version of totally
ordered sets this summer.
- kcrisman
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