id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
16884,Quasi-difference matrices (database+is_QDM),ncohen,,"A new database entry for quasi-difference matrices. As a result:
- The Vmt vectors are added to the quasi-difference matrices database entry, and not anymore to `OA_constructions`
- The old OA constructions based on QDM are converted to QDM constructors.
- The OA constructor now queries the QDM database entry (and so it gets the QDM+Vmt)
Two notes:
- There is no `is_quasi_difference_matrix` right now, so the QDM are tested through the OA they generate.
- There is no `designs.quasi_difference_matrix` because I did not know how to write it in such a way that it would be easy to find a QDM that builds an OA. The problem is that a QDM is defined with 5 parameters `(n,_,_,_,u)` and that the `n` of an `OA(k,n)` is the sum `n+u`. Consequently, if you want to build an `OA(k,n)` from a QDM you must try all pairs `n'+u = n` and that's a waste of time.
- Right now the DM are not added to the dictionary of QDM. I did not see the point, given that the DM are already queried by `orthogonal_arrays()` through their constructor (which will also contain additional constructions of DM).
",enhancement,closed,major,sage-6.4,combinatorial designs,fixed,,vdelecroix,,Nathann Cohen,Vincent Delecroix,N/A,,f0b7bab049e078a663702a935ea5f09facd396ed,f0b7bab049e078a663702a935ea5f09facd396ed,#16879,