On Tue, Dec 06, 2005 at 07:47:57PM +0100, Mikael Nilsson <[EMAIL PROTECTED]> was heard to say: > tis 2005-12-06 klockan 10:12 -0800 skrev Daniel Burrows: > > not terribly interested in adding more ways to throw away solutions > > entirely, > > as the more complicated you make those schemes, the more likely that they'll > > eliminate solutions that are actually good. For instance, saying "never > > remove packages that are to be upgraded" fails when you're upgrading two > > packages A and B, where the newer version of A conflicts with B. > > I fully understand that. However, I see no reason why solutions that > contradict your orders should ever come *before* options that obey your > orders. I would very much like to know what the potential negative > consequences of a (very) high default value for that option might be? > I'll definitely try it out and report back. Especially now that the > complex C++ allocator transition is ongoing, I have these situations > quite often...
The main reason this isn't implemented is that I haven't had the time to analyze it and figure out a good solution. It might be as simple as tweaking the score of each non-automatic non-kept package, but I'd want to think about that and run some tests before making the change. On Tue, Dec 06, 2005 at 08:36:51PM +0100, Mikael Nilsson <[EMAIL PROTECTED]> was heard to say: > tis 2005-12-06 klockan 10:47 -0800 skrev Daniel Burrows: > > The option is actually Aptitude::ProblemResolver::PreserveManualScore; > > no hyphen. This is contrary to the documentation, which I've now fixed. > > The reason that this is not a very strong imperative is that it forces > > the program to try *very hard* to preserve the states of manual packages. > > This in turn means that it can be difficult to find any solution at all > > (indeed, I was able to quickly guide the search to a solution without > > setting this; with this option, it ran out of solutions almost right away). > > That's certainly a negative side effect... I wasn't expecting that - I > was expecting more or less a reordering of solutions. Oh well, I guess > it can be hard to predict such algorithms. The thing is that scoring is used to decide where to search. If every action makes things worse, you end up looking at the whole search space before finding a solution. Daniel
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