Hi again, On Thu, Jun 23, 2011 at 01:06:44PM +0200, Joachim Breitner wrote:
> > But according to our experience, for it to happen > > the problem should not be underestimated and, more importantly, should > > be properly formalized in a way which is independent of some specific > > encoding technique. > > Correct. That is why I suggested to use the format already used in a > MAX-SAT competition: > http://maxsat.ia.udl.cat/requirements/ In fact, from out point of view the DIMACS format or MAX-SAT input format are already a specific encoding technique, and we think that one should first find a logical specification of what exactly one tries to achieve, before thinking about a specific encoding into MAX-SAT or whatever other solver technology. One way of formalising this could be stated in the following style: 1) one defines first a certain abstraction of a distribution (like ignoring certain kinds of conflicts). This has of course to be exactly defined. Lets call this function a(). 2) lets say that the result of migration a set m to a testing distribution t is denoted as "t+m" 3) then you say: you look for a migration set m, such that for the testing distribution t: every "interesting" installation request that is satisfiable in a(t) is also satisfiable in a(t+m) Ideally, a() would be the identity function, that is no abstraction at all. The important question here would be to define what are precisely the "interesting" installation requests. Candidates are: - install one arbitrary single package A. This seems to be the definition currently used in britney. - install an arbitray *set* of packages together. This might be interesting in some cases, but seems to be too restrictive. Another element of the precise specification would be: one wants to have a maximal solution. What precisely is the sense of maximality here? Maximal number of binary packages? Maximal number of source packages? Should there be a way to give more weight to more "important" packages? Cheers -Zack and Ralf. -- Ralf Treinen Laboratoire Preuves, Programmes et Systèmes Université Paris Diderot, Paris, France. http://www.pps.jussieu.fr/~treinen/ -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/[email protected]
