?- solve(numbers(7,7,6,5,3),goal(6)).
NUMBERS = {7 7 6 5 3} GOAL = 6
considering rule 1 ...
considering rule 2 ...
considering rule 3 ...
considering rule 4 ...
application of rule 4 produces ( 6 + (  ( 7 - 7 ) *  ( 5 * 3 ) ) )
true .

?- solve(numbers(2,2,1,5,9),goal(9)).
NUMBERS = {2 2 1 5 9} GOAL = 9
considering rule 1 ...
considering rule 2 ...
considering rule 3 ...
considering rule 4 ...
application of rule 4 produces ( 9 + (  ( 2 - 2 ) *  ( 1 * 5 ) ) )
true .

?- solve(numbers(3,2,2,1,1),goal(3)).
NUMBERS = {3 2 2 1 1} GOAL = 3
considering rule 1 ...
considering rule 2 ...
considering rule 3 ...
considering rule 4 ...
application of rule 4 produces ( 3 + (  ( 2 - 2 ) *  ( 1 * 1 ) ) )
true .