Well, I decided to post my thoughts on this in a longer form after all.
xspeedballx wrote:Can every dungeon be completed purist every time?(Let's ignore bugs for now, the screwed thread highlights those nicely).
Isn't the "screwed" thread just a bunch of examples of unsolvable dungeons? You declare unsolvable dungeons as bugs, then ask whether there are unsolvable dungeons when ignoring these bugs. This does not make sense. Make up your mind.
Also, I suspect the only way to *guarantee* a dungeon is solvable is to find a solution, and this is just not practical to do on level generation due to cpu time constraints (finding one solution can be fairly fast, finding out that there isn't one can take a while if you're not blocked in right at the start). And dislekcia just said even the devs currently don't have a solver, so they *cant* guarantee that a dungeon is solvable in this way.
The number of winning sequences of actions in a randomly generated dungeon is random, and I cant see any reason why it could not sometimes randomly be 0. The only way this could be prevented is somehow excluding unsolvable dungeons from generation, which as I explained above, is not done. The probability that there is no winning sequence of actions may be small, but if it is not exactly 0, with enough tries you *will* generate an unsolvable dungeon.
So the answer is no.
Edit: vetoing dungeon instances with early blocks is probably possible and practical (for example by checking whether there are paths to a bunch of low level monsters), and might be done. It's probably also possible and practical for some other causes of unwinnable dungeons, and maybe some are vetoed. I just don't know. If this is the case you would have to be really unlucky to hit an unsolvable dungeon.