Re: Counting backtracks

Karen Petrie (scomkep@zeus.hud.ac.uk) wrote
>...
> Then you need to redefine the event handler:
> 
> write_info(_Error, Predicate):-
>         arg(1, Predicate, Minimum),
>         printf("Found a solution with cost %d \n", [Minimum]),
>         get_backtracks(B),
>         printf("Backtracks to this point = %d \n \n", [B]).
> 
> %set event handler
> :- set_event_handler(280, write_info/2).
> 
> Then all you do is call minimize on your labelling:
> 
> minimize(mylabeling(SearchVars), OptimalNumber)


There is actually no need to use this obscure event handler.
You can simply write:

    minimize((
	    mylabeling(SearchVars),
            get_backtracks(B),
            printf("Backtracks to this point = %d \n \n", [B])
	), OptimalNumber)

Whenever mylabeling/1 succeeds, you have a better solution.


-- 
 Joachim Schimpf              /             phone: +44 20 7594 8187
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