id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
18469,Tensor product of crystals does not handle -inf for epsilon/phi correctly,tscrim,sage-combinat,"This does not work:
{{{
sage: E1 = crystals.elementary.B(['A',2], 1)
sage: E2 = crystals.elementary.B(['A',2], 2)
sage: T = crystals.TensorProduct(E1, E2)
sage: x = T(E1.module_generators[0], E2.module_generators[0]); x
[0, 0]
sage: x.f(1)
[-1, 0]
sage: x.e(1)
[1, 0]
}}}
The reason is because we try and be clever with how we compute the `_sig` and do an `epsilon_(k) - phi_i(k-1)`. If one of these (in particular, the phi) is `-inf`, then the computation breaks down. Instead, we have to bite the bullet and do the partial sums of the weight pairings to make sure we cover these cases.",defect,closed,major,sage-6.8,combinatorics,fixed,"crystals, tensor product",sage-combinat bsalisbury1 aschilling,,Travis Scrimshaw,Ben Salisbury,N/A,,9a24ea03c2a5a4268224cc34230681bbb8b92190,9a24ea03c2a5a4268224cc34230681bbb8b92190,,