All examples in this Bongard Problem are oblong connected figures made up of some curves.

Shapes as tall as they are wide would be ambiguous.

M. M. Bongard, Pattern Recognition, Spartan Books, 1970, p. 216.

Adjacent-numbered pages:
BP2 BP3 BP4 BP5 BP6  *  BP8 BP9 BP10 BP11 BP12

easy, nice, dual, handed, rotate, stretch, finished, traditional, bongard

Multiple options:
figure_made_of_curves [smaller | same | bigger],
oblong_axis_aligned_figure_made_of_curves [smaller | same | bigger]

Mikhail M. Bongard

All examples in this Problem show one or more connected figures made up of lines.

Some big shapes and some small shapes would be ambiguous.

M. M. Bongard, Pattern Recognition, Spartan Books, 1970, p. 218.

See BP2 for the same idea using one shape.

Adjacent-numbered pages:
BP9 BP10 BP11 BP12 BP13  *  BP15 BP16 BP17 BP18 BP19

fuzzy, size, stable, finished, traditional, bongard

curves_drawing [smaller | same | bigger]

Mikhail M. Bongard

M. M. Bongard, Pattern Recognition, Spartan Books, 1970, p. 230.

BP152 is the same solution (with the sides switched), using connected shapes and without black filling.

BP1206 was created to be a slightly different version of this: "vertical axis of symmetry vs. no vertical axis of symmetry." (That less specific solution fits this Bongard Problem as well.)

Adjacent-numbered pages:
BP45 BP46 BP47 BP48 BP49  *  BP51 BP52 BP53 BP54 BP55

nice, stretch, left-narrow, finished, traditional, bongard

curves_and_fill_shapes_separate_drawing [smaller | same | bigger]

Mikhail M. Bongard

M. M. Bongard, Pattern Recognition, Spartan Books, 1970, p. 244.

BP1226 is "three identical elements vs. other number of identical elements".

Adjacent-numbered pages:
BP86 BP87 BP88 BP89 BP90  *  BP92 BP93 BP94 BP95 BP96

number, ignoreimperfections, finished, traditional, bongard

curves_and_fill_shapes_drawing [smaller | same | bigger]

Mikhail M. Bongard

Adjacent-numbered pages:
BP114 BP115 BP116 BP117 BP118  *  BP120 BP121 BP122 BP123 BP124

fuzzy, traditional

curves_drawing [smaller | same | bigger]

Douglas R. Hofstadter

This refers to all Bongard Problem solution ideas. No need to be a particularly well-made or well-defined Bongard Problem.

Adjacent-numbered pages:
BP536 BP537 BP538 BP539 BP540  *  BP542 BP543 BP544 BP545 BP546

notso, meta (see left/right), links, world, left-self, right-null, left-it, feedback

everything [smaller | same]
zoom in left (bp)

Aaron David Fairbanks

Adjacent-numbered pages:
BP537 BP538 BP539 BP540 BP541  *  BP543 BP544 BP545 BP546 BP547

notso, meta (see left/right), links, oebp, world, left-self, right-null, left-it, feedback

everything [smaller | same]
zoom in left (bppage)

Aaron David Fairbanks

All ideas and things, with no limits.

Adjacent-numbered pages:
BP539 BP540 BP541 BP542 BP543  *  BP545 BP546 BP547 BP548 BP549

notso, meta (see left/right), links, world, left-self, right-finite, right-full, left-null, left-it, feedback, experimental, funny

everything [smaller | same]
zoom in left (everything) | zoom in right (nothing)

Aaron David Fairbanks

Left-sorted BPs have the keyword "notso" on the OEBP.

This meta Bongard Problem is about Bongard Problems featuring two rules that are conceptual opposites.

Sometimes both sides could be seen as the "not" side: consider, for example, two definitions of the same Bongard Problem, "shape has hole vs. does not" and "shape is not filled vs. is". It is possible (albeit perhaps unnatural) to phrase the solution either way when the left and right sides partition all possible relevant examples cleanly into two groups (see the allsorted keyword).

When one property is "positive-seeming" and its opposite is "negative-seeming", it usually means the positive property would be recognized without counter-examples (e.g. a collection of triangles will be seen as such), while the negative property wouldn't be recognized without counter-examples (e.g. a collection of "non-triangle shapes" will just be interpreted as "shapes" unless triangles are shown opposite them).

BP513 (keyword left-narrow) is about Bongard Problems whose left side can be recognized without the right side. When a Bongard Problem is left-narrow and not "right-narrow that usually makes the property on the left seem positive and the property on the right seem negative.

The OEBP by convention has preferred the "positive-seeming" property (when there is one) to be on the left side.

All in all, the keyword "notso" should mean:

1) If the Bongard Problem is "narrow" on at least one side, then it is left-narrow.

2) The right side is the conceptual negation of the left side.

If a Bongard Problem's solution is "[Property A] vs. not so", the "not so" side is everything without [Property A] within some suitable context. A Bongard Problem "triangles vs. not so" might only include simple shapes as non-triangles; it need not include images of boats as non-triangles. It is not necessary for all the kitchen sink to be thrown on the "not so" side (although it is here).

See BP1001 for a version sorting pictures of Bongard Problems (miniproblems) instead of links to pages on the OEBP. (This version is a little different. In BP1001, the kitchen sink of all other possible images is always included on the right "not so" side, rather than a context-dependent conceptual negation.)

Contrast keyword viceversa.

"[Property A] vs. not so" Bongard Problems are often allsorted, meaning they sort all relevant examples--but not always, because sometimes there exist ambiguous border cases, unclear whether they fit [Property A] or not.

Adjacent-numbered pages:
BP862 BP863 BP864 BP865 BP866  *  BP868 BP869 BP870 BP871 BP872

notso, meta (see left/right), links, keyword, left-self, funny

everything [smaller | same]
zoom in left

Aaron David Fairbanks

Although this Bongard Problem is self-referential, it's only because of the specific phrasing of the solution. "BP902 vs. anything else" would also work. The number 902 could have been chosen coincidentally.

See BP953, BP959.

Adjacent-numbered pages:
BP897 BP898 BP899 BP900 BP901  *  BP903 BP904 BP905 BP906 BP907

notso, meta (see left/right), links, left-self, left-narrow, left-finite, left-full, right-null, right-it, invalid, experimental, funny

everything [smaller | same]
zoom in left (bp902)

Leo Crabbe