All examples in this Bongard Problem are solid black shapes.
BP345 is "Intersection of circle and square vs. union of circle and square."
Adjacent-numbered pages: BP1267 BP1268 BP1269 BP1270 BP1271  *  BP1273 BP1274 BP1275 BP1276 BP1277
EX1 is ambiguous because it might be a small circle minus a large square, or a small square minus a large circle.
easy, nice, precise
Ben