This is a problem with all types of search. If you do not visit all the oponent responses then you can not be certain that about a capture. The point I was trying to make was that You CAN use heuristics to direct a PN type search. There seemed to be a perception that you had to ignore any move ordering information when using PN. This is not the case (maybe this idea needs/has a different name ?) By using ordering you are more likely to visit a node that will will tell you that there is no point visiting it's siblings. Thus saving work. For your information I do not build a complete tree with the set of "better" moves. Each node has proof numbers associated with types of move (like a child node waiting to expand). By using higher proof numbers for more speculative moves you avoid visiting these until the alternative branches reach a level of complexity greater than the assigned value. This gives you a search that tries speculative moves when the more hopeful ones lead to complex (wide) searches. One of the reasons I implemented a PN type scheme was because I could not see how other searches could achieved this type of effect. cheers Paul. Chris Fant wrote:
I believe that PN combinbed with heuristics is the best way foward for solving GO problems. But your proof statement should be in terms of heuristics goals that prune the search. (e.g. can I capture using only the suggested moves with a heuristic greater than a given value). This initially gives you a result that can be refined by lowering the value to expand the tree.The thing I don't understand about that is: If you are only using the suggested moves, how can you be sure that you do actually capture. What it the opponent has a move that was not suggested in the search that can prohibit the capture?