Thank you for taking the time to answer. On 18/04/07, Mikael Zayenz Lagerkvist <[EMAIL PROTECTED]> wrote:
When the search-procedure recomputes a node, it will not follow exactly the same path as the first time - several branching decisions are added at once and then a fixpoint is computed (this is called batch recomputation). If this fails, the an error such as the one you observed might be thrown. This is one potential cause for your problem.
If i turn off re-computation i no longer suffer this problem, so this could very well be the source of my problem.
One of the key properties that Gecode uses for enabling batch recomputation this is that propagators should be monotonic. Typical cases where propagators are non-monotonic might be: not subscribing to all events used, using heuristic/random propagation algorithms, reporting ES_FIX when that is not the case, and of course general bugs.
I think what i am working on fits nicely into the category of heuristic propagation. The propagator in question is not generally monotonic (ie it might detect in-feasibility on one set of domains and neglect to spot in-feasibility of a stricter set of domains) and in addition the result of assign, propagate, assign,propagate and assign,assign, propagate, propagate is not guaranteed to be the same. Propagation is however completely deterministic. So i guess this should be the source of my problem, right? I suppose i will just have to run without re-computation. Thank your for explaining this. The propagator im working with is a bit 'special' so i suppose it isn't too surprising that im encountering this type of issue :) Peter Tiedemann _______________________________________________ Gecode users mailing list [EMAIL PROTECTED] https://www.gecode.org/mailman/listinfo/gecode-users
