%% Copy rules and delete rules

% Schema
%-------
database({g(X:string, Y:string, C:integer)}).

%Derivated predicates and rules
%------------------------------
solved(0, 'a').		% nodes solved so far

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

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

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

export prim(I, X).