Left Bongard Problems do not have to sort all relevant examples; if they would leave some border cases unsorted, it just has to be clear precisely which examples those would be.

Often a precise divide between values on a spectrum comes from intuitively "crossing a threshold." For example, there is an intuitive threshold between acute and obtuse angles. Two sides of a Bongard Problem on opposite ends of a threshold, coming close to it, are interpreted as having precise divide between sides, right up against that threshold.

See BP508 for the version with links to pages on the OEBP instead of images of Bongard Problems.

Adjacent-numbered pages:
BP871 BP872 BP873 BP874 BP875  *  BP877 BP878 BP879 BP880 BP881

hard, notso, challenge, meta (see left/right), miniproblems, creativeexamples, assumesfamiliarity, structure, presentationinvariant

bpimage_shapes [smaller | same | bigger]
zoom in left (bpimage_shapes_exact_sort)

Aaron David Fairbanks

"Allsorted" Bongard Problems (BP875^left) always fit as right examples.

Left examples are never "allsorted".

Adjacent-numbered pages:
BP873 BP874 BP875 BP876 BP877  *  BP879 BP880 BP881 BP882 BP883

hard, challenge, meta (see left/right), miniproblems, creativeexamples, assumesfamiliarity, structure, presentationinvariant

bpimage_shapes_exact_sort [smaller | same | bigger]
zoom in left | zoom in right (bpimage_shapes_exact_sort_no_midway)

Aaron David Fairbanks