Here’s my attempt to write wolf-sheep-cabbage using tabling. It fails under 8.1.14 What am I doing wrong? it’s pure afaik? :- module(wsc, [go/1]). go(Moves) :- wsc(0,0,0,0, Moves). :- table wsc/5. wsc(1,1,1,1, []). % goal wsc(0,W,S,C, [lr(f) | Rest]) :- % farmer moving alone c(0,W,S,C…

[image] peter.ludemann: A solution that I proposed to David S. Warren was to allow allow specifying that an argument shouldn’t be tabled at all because it’s recording information about the computation (in this case, the moves in the puzzle). But he wasn’t happy with that idea and eventually I so…

I tried first to comment out the table directive, and use iterative deepening: it works of course, yielding the solution ?- length(L,_),go(L). L = [lr(s), rl(f), lr(w), rl(s), lr(c), rl(f), lr(s)] . Meanwhile, I was thinking about mode directed tabling (Jan answer was not yet there…), indeed just …

[image] jan: answer subsumption In this case, table wsc(_,_,_,_,first) works but table wsc(_,_,_,_,last) goes into an infinite loop, as expected; so all wouldn’t be a viable mode unless there were also a way to look at results and prune them by checking for circularity. I found this paper: T…

[image] peter.ludemann: are there others you can suggest? That was the one I was primarily referring to. Thanks for finding. I vaguely recall there is more, but I’m not sure. [image] peter.ludemann: I couldn’t find any documentation on what happens if the call to Pred AFAIK, the la…

[image] peter.ludemann: I found this paper: Tabling with Sound Answer Subsumption (this will take me a while to read!) Is the paper worthy of adding to Useful Prolog references Papers section? Since I haven’t used tabling yet, I don’t know if this out on the extreme or a good general paper. …

I’d rate it a pretty advanced topic. There is a lot more to say about tabling that would help people much more and that is nowhere documented. The most concrete are probably various sections of the XSB manual. David Warren once started on a book, but there is not more than a draft with, AFAIK n…

[image] jan: think it isn’t even documented in the XSB manual As far as I can tell, fold isn’t documented in the XSB manual. There’s this compiler option (which I don’t understand): unfold_off When specified, singleton sets optimizations are not performed during specialization. This option…

[image] peter.ludemann: unfold_off I think that is related to code specialization, not to the fold(pred) option of tabling under answer subsumption (but I could be wrong). [image] peter.ludemann: I would suggest throwing an error in that case Might make sense. As I read the code, fai…

[image] EricGT: That sounds like the halting problem . I’m starting to think you’re right about that. The tabling mode first gives a hint … it gives a single solution that (I think) is guaranteed to not have a loop. But subsequent solutions (including last) aren’t prevented from infinite back…

Picat claims to be able to solve this problem, and produce a list of actions, using “tabling”. Does anyone on this list know Picat, and can explain how this is done? ( http://picat-lang.org/ Example 4)

Tabling the wolf, sheep, cabbage

Help!

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Tabling the wolf, sheep, cabbage

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