//licenceplate(x, y) = _ <: (opening_line(x, y, 4), closing_line(x, y, 2) : threshold(x, 1, 50), threshold(x, 150, 255) : and : opening_column(x, y, 4) : opening_line(x, y, 4) : dilations_square(x, y, 4)), _ : and;
//licenceplate(x, y) = _ <: (opening_line(x, y, 4), closing_line(x, y, 2) : threshold(x, 1, 50), threshold(x, 150, 255) : and : opening_column(x, y, 4) : opening_line(x, y, 4) : dilations_square(x, y, 4)), _ : and;