See BP929 for distinction between sequences of arbitrary length and sequences of fixed length (keywords "sequence" and "fixedsequence").
Zero, one, or two objects may technically form a sequence, but if ALL examples of a BP have zero, one, or two objects, we do not consider that BP to be about sequences.
See BP929 for distinction between sequences of arbitrary length and sequences of fixed length.
Bongard Problems about sequences vs. other Bongard Problems.
Aaron David Fairbanks