% RUNS ON flatzinc
% RUNS ON fzn_fd_canon
% RUNS ON fzn_fdlp_canon
% RUNS ON fzn_lazyfd_canon
% RUNS ON fzn_sat_canon

var bool: x1 :: output_var;
var bool: x2 :: output_var;
constraint bool_clause([true], []);
constraint bool_clause([], [false]);
constraint bool_clause([true], [true]);
constraint bool_clause([true], [false]);
constraint bool_clause([false], [false]);
constraint bool_clause([x1], [x2]);
solve satisfy;