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bb_probe(++From, ++To, +Goal, ?Template, ?Cost, ++Handle, ++Module)

Low-level primitive for building branch-and-bound-style search procedures


bb_probe tries to find a solution for Goal in the range From..To. If there is a solution, its Template and Cost are stored in Handle, the computation is undone, and bb_probe succeeds. If there is no solution, Handle is not changed and bb_probe fails. The primitive set_var_bounds/3 is used to impose cost bounds during the search process in a generic way.


% a simple branch-and-bound procedure
my_minimize(Goal, Cost, Solution, OptCost, Module) :-
	bb_init(1000000, Handle),
	    bb_delta(0, 1000000, Goal, Cost, Handle, Module)
	    bb_solution(Handle, Solution),
	    bb_cost(Handle, OptCost)

bb_delta(From, To, Goal, Cost, Handle, Module) :-
	bb_probe(From, To, Goal, Goal, Cost, Handle, Module),
	NewTo is bb_cost(Handle) - 1,
	bb_delta(From, NewTo, Goal, Cost, Handle, Module).

See Also

bb_init / 2, bb_cost / 2, bb_solution / 2, bb_finish / 1, bb_min / 3, bb_min / 6, set_var_bounds / 3