%% Pigeon Hole example.

% Number of Holes
% const n=9.

% There are n+1 pigeons.
pigeon(1..n+1).

% There are n holes.
hole(1..n).

% Select exactly one hole for each pigeon.
1{ in_hole(P,H)  : hole(H) }1 :-  pigeon(P). 

% If there are 2 pigeons in a hole then infer False.
:- 2{ in_hole(P,H) : pigeon(P) }, hole(H).