https://en.wikipedia.org/wiki/Opaque_set
Adjacent-numbered pages: BP1242 BP1243 BP1244 BP1245 BP1246  *  BP1248 BP1249 BP1250 BP1251 BP1252
precise, allsorted, unwordable, notso
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Leo Crabbe
Any small amount of convexity along the grey border will cause an example to fit right.
Adjacent-numbered pages: BP1243 BP1244 BP1245 BP1246 BP1247  *  BP1249 BP1250 BP1251 BP1252 BP1253
precise, allsorted, unwordable, notso, perfect