On Tue, Dec 28, 2010 at 03:47:22PM +0100, Julian Andres Klode wrote: > Not really, you can declare literals more or less important than > others which deals with almost every case I throw at it. > > /* Keep manually installed packages or installed packages that are > * candidates on the system and non-candidates away if possible. */ > if (is_installed && (!is_automatic || cand == ver)) > picosat_set_more_important_lit(var(ver)); > else if (!is_installed && cand != ver) > picosat_set_more_important_lit(var(ver)); Problem is: by doing this, you're now adding quite some implicit requirements not only on a SAT solver (which is just one among several possible solving techniques), but also on a solver that supports an interface like the above. The possibility of changing the solver according to a standardized interface of the user is, if not jeopardized, significantly diminished. > The solver will first try to solve the problems by setting > non-candidate versions to -1 and installed versions (manually > installed or candidates) to 1 and then trying other solutions. It sounds like it will explode pretty soon. Have you tried running it with several suites (e.g. stable+testing+unstable) trying to install packages from the non-default-candidate suite? Don't get me wrong, I'm far from being in a position of arguing in favor or against any specific solver. Nonetheless I'm more than convinced that blessing a specific solver is risky as it's very difficult, later on, to get rid of the implicit requirements that the blessing poses. In looking for a better solver than current APT's, it is worth to make an effort to standardize over an interface that makes no assumptions on specific solving techniques. It does not necessarily need to be CUDF, but it should have some of its good properties, like solver technique independence. (i.e. AOL on Pietro's mail) Cheers. -- Stefano Zacchiroli -o- PhD in Computer Science \ PostDoc @ Univ. Paris 7 zack@{upsilon.cc,pps.jussieu.fr,debian.org} -<>- http://upsilon.cc/zack/ Quando anche i santi ti voltano le spalle, | . |. I've fans everywhere ti resta John Fante -- V. Capossela .......| ..: |.......... -- C. Adams
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