BP979 is very similar: whether a particular square can be deduced from the rest.
Adjacent-numbered pages: BP1253 BP1254 BP1255 BP1256 BP1257  *  BP1259 BP1260 BP1261 BP1262 BP1263
notso, rules, grid, miniworlds
grid_of_images_with_rule [smaller | same | bigger]
Aaron David Fairbanks