#16269: Cartesian Products of additive groups
-------------------------------------+-------------------------------------
       Reporter:  ncohen             |        Owner:
           Type:  enhancement        |       Status:  needs_review
       Priority:  major              |    Milestone:  sage-6.2
      Component:  categories         |   Resolution:
       Keywords:                     |    Merged in:
        Authors:  Nathann Cohen,     |    Reviewers:
  Nicolas M. ThiƩry                  |  Work issues:
Report Upstream:  N/A                |       Commit:
         Branch:  u/ncohen/16269     |  aa07ba19487569ef26772c51092c4d5342faff7c
   Dependencies:                     |     Stopgaps:
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Comment (by dimpase):

 Replying to [comment:6 ncohen]:
 > Yo !
 >
 > > Hmm, do you mean to construct the Cartesian product of fields? Then it
 will be a ring, with two operations, addition and multiplication...
 >
 > Hmmmm.. Well, I guess it may not be very hard to do.
 >
 > 1) A ring is a additive group (so the + is already implemented) for the
 product of rings

 You can make any abelian group into a ring by defining multiplication by a
 non-zero element a to be identity operation, i.e. ax=x for all x in the
 group, and by 0 to be zero, i.e. 0x=0 for all x in the group.
 This should be easy to implement - no real code, just some abstract
 nonsense :-)

 That is, as soon as you have cartesian product of rings, you have what you
 need in general...

 >
 > 2) It has a multiplicative operation, but perhaps the product of
 multiplicative associative magma is not detected as such.
 but why?
 Is it because #10963 will take forever to merge, as it has apparently hit
 some kind of OSS unsolvability barrier? :)


 > If you can just give Sage the right inheritances, perhaps you have no
 real code to implement.
 If I were a category theorist and a (C)Python guru by training, perhaps it
 will only take me 5 minutes ;-)

--
Ticket URL: <http://trac.sagemath.org/ticket/16269#comment:13>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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