LDL++ Source Code

database( {
    g( From:string, To:string, Cost:integer) 
}).

solved(0, a).          % nodes solved so far

prim(I+1, l_c<(X, Y, C)>) <- solved(I, X), g(X, Y, C), ~solved(I,Y).

solved(I+1, X) <- solved(I, X).
solved(I, Y) <- prim(I, (X, Y, C)).

single(l_c, (X, Y, C), (X,Y, C)).
multi(l_c, (X1, Y1, C1), (X2, Y2, C2), (X2, Y2, C2)) <- C2 <C1.
multi(l_c, (X1, Y1, C1), (X2,Y2, C2), (X1, Y1, C1)) <- C2 >= C1.

edges(X, Y, C) <- prim(_, (X, Y, C)).

export edges(X, Y, C).