Left-sorted Bongard Problems have the the keyword "left-narrow" on the OEBP.

Call a rule "narrow" if it is likely to be noticed in a large collection of examples, without any counterexamples provided.

A collection of triangles will be recognized as such; "triangles" is a narrow rule. A collection of non-triangular shapes will just be seen as "shapes"; "not triangles" is not narrow.

Intuitively, a narrow rule seems small in comparison to the space of other related possibilities. Narrow rules tend to be phrased positively ("is [property]"), while non-narrow rules opposite narrow rules tend to be phrased negatively ("is not [property]").

Both sides of a Bongard Problem can be narrow, e.g. BP6.

Even a rule and its conceptual opposite can be narrow, e.g. BP20.

A Bongard Problem such that one side is narrow and the other side is the non-narrow opposite reads as the narrow side being a subset of the other. See BP881.

What seems like a typical example depends on expectations. (See the keyword assumesfamiliarity for Bongard Problems that require the solver to go in with special expectations.)

A person might notice the absence of triangles in a collection of just polygons, because a triangle is such a typical example of a polygon. On the other hand, a person will probably not notice the absence of 174-gons in a collection of polygons.

Typically, any example fitting a narrow rule can be changed slightly to no longer fit. (This is not always the case, however. Consider the narrow rule "is approximately a triangle".) See the keyword stable.

It is possible for a rule to be "narrow" (communicable by a properly chosen collection of examples) but not clearly communicated by a particular collection of examples satisfying it, e.g., a collection of examples that is too small to communicate it.

Note that this is not just BP514 (right-narrow) flipped.

Is it possible for a rule to be such that some collections of examples do bring it to mind, but no collection of examples unambiguously communicates it as the intended rule? Perhaps there is some border case the rule excludes, but it is not clear whether the border case was intentionally left out. The border case's absence would likely become more conspicuous with more examples (assuming the collection of examples naturally brings this border case to mind).

See BP830 for a version with pictures of Bongard Problems (miniproblems) instead of links.

Adjacent-numbered pages:
BP508 BP509 BP510 BP511 BP512  *  BP514 BP515 BP516 BP517 BP518

dual, meta (see left/right), links, keyword, side

bp [smaller | same | bigger]

Aaron David Fairbanks

Left-sorted Bongard Problems have the the keyword "right-narrow" on the OEBP.

This sorts Bongard Problems based on how BP513 (left-narrow) would sort them if they were flipped; see that page for a description.

Adjacent-numbered pages:
BP509 BP510 BP511 BP512 BP513  *  BP515 BP516 BP517 BP518 BP519

dual, meta (see left/right), links, keyword, side

bp [smaller | same | bigger]

Aaron David Fairbanks

Left-sorted BPs have the keyword "left-finite" in the OEBP.

How to distinguish between different examples depends on the Bongard Problem. For example, in BPs about little black dots, examples may be considered the same when they have the same number of dots in all the same positions.

Note that this is not just BP516 (right-finite) flipped.

"Left-finite" implies left-narrow.

See left-listable, which is about an infinite left side that can be organized into a neverending list versus infinite left side that cannot be organized into a neverending list.

"Left-finite" BPs are typically precise.

See BP1032 for a version that sorts images of Bongard Problems (miniproblems) instead of links, and which only sorts images of Bongard Problems about numbers.

Adjacent-numbered pages:
BP510 BP511 BP512 BP513 BP514  *  BP516 BP517 BP518 BP519 BP520

notso, dual, meta (see left/right), links, keyword, side

bp [smaller | same | bigger]
zoom in right (bp_infinite_left_examples)

Aaron David Fairbanks

Left-sorted BPs have the keyword "right-finite" in the OEBP.

BPs are sorted based on how BP515 (left-finite) would sort them were they flipped; see that page for a description.

"Right-finite" implies right-narrow.

See right-listable, which is about an infinite right side that can be organized into a neverending list versus infinite right side that cannot be organized into a neverending list.

"Right-finite" BPs are typically precise.

See BP1041 for a version that sorts images of Bongard Problems (miniproblems) instead of links, and which only sorts images of Bongard Problems about numbers.

Adjacent-numbered pages:
BP511 BP512 BP513 BP514 BP515  *  BP517 BP518 BP519 BP520 BP521

notso, dual, meta (see left/right), links, keyword, side

bp [smaller | same | bigger]
zoom in right (bp_infinite_right_examples )

Aaron David Fairbanks

Left-sorted BPs have the keyword "left-self" on the OEBP. Right-sorted BPs have the keyword "right-self."

These keywords are added to pages automatically.

Rhetorical questions: Where does this BP sort itself? Where does this BP sort the flipped version of itself?

See BP793 for the version sorting pictures of Bongard Problems (miniproblems) instead of links to pages on the OEBP.

See BP1075 for an example of a BP that is tagged "left-self" but would still be tagged "left-self" after the sides in the title were flipped. (This is unusual; a "left-self" BP after being flipped is typically "right-self" and vice versa.)

Adjacent-numbered pages:
BP512 BP513 BP514 BP515 BP516  *  BP518 BP519 BP520 BP521 BP522

nice, dual, meta (see left/right), links, keyword, side, metameta, feedback

Multiple options:
linksbp [smaller | same | bigger],
bp_in_own_world [smaller | same | bigger]
zoom in left | zoom in right

Aaron David Fairbanks

Rhetorical question: Where does this Bongard Problem sort an image of itself?

See BP999 and BP1004 for similar paradoxes.

Bongard Problems fitting left here evidently come in three categories: 1) would sort all Bongard Problems with the same solution left, 2) would sort all Bongard Problems with the same solution right, or 3) would sort some Bongard Problems with the same solution left and some right. See BP927.

See BP517 for the version with links to pages on the OEBP instead of images of Bongard Problems (miniproblems).

See BP954, which is about Bongard Problems not only sorting themselves, but moreover fractally appearing in themselves as panels.

Adjacent-numbered pages:
BP788 BP789 BP790 BP791 BP792  *  BP794 BP795 BP796 BP797 BP798

hard, nice, abstract, dual, handed, leftright, solved, meta (see left/right), miniproblems, creativeexamples, presentationmatters, assumesfamiliarity, structure, experimental

boxes_bpimage_sorts_self [smaller | same | bigger]
zoom in left (boxes_bpimage_sorts_self_left) | zoom in right (boxes_bpimage_sorts_self_right)

Aaron David Fairbanks

"BONGARD HELL."

This the flipped version of BP793 but using only images of Bongard Problems with solution "__ half more black/less white than other half versus vice versa," that all use rotated, reflected, and inverted versions of the same examples.

See BP971 (left vs. right more black) and BP972 (top vs. bottom more black).

Adjacent-numbered pages:
BP790 BP791 BP792 BP793 BP794  *  BP796 BP797 BP798 BP799 BP800

hard, nice, abstract, dual, handed, leftright, meta (see left/right), miniproblems, presentationmatters, left-finite, right-finite, assumesfamiliarity, structure, experimental, funny

bongard_hell [smaller | same | bigger]
zoom in left | zoom in right

Aaron David Fairbanks

See BP567 for the version with links to pages on the OEBP instead of images of Bongard Problems (miniproblems).

Adjacent-numbered pages:
BP791 BP792 BP793 BP794 BP795  *  BP797 BP798 BP799 BP800 BP801

hard, nice, abstract, dual, handed, leftright, challenge, meta (see left/right), miniproblems, creativeexamples, assumesfamiliarity, structure, presentationinvariant

boxes_bpimage [smaller | same | bigger]

Aaron David Fairbanks

Left: the left hand side is enough to communicate the answer; the left pattern can be seen without the counterexamples on the right.

Right: the right hand side is enough to communicate the answer; the right pattern can be seen without counterexamples on the left.

Flipping a BP will switch its sorting.

The following is taken from the comments on page BP513 (keyword left-narrow):

Call a pattern "narrow" if it is likely to be noticed in a collection of examples, without any counterexamples provided.

A collection of triangles will be recognized as such; "triangles" is a narrow pattern. A collection of non-triangular shapes will just be seen as "shapes"; "not triangles" is not narrow.

Narrow patterns tend to be phrased positively ("is [property]"), while non-narrow patterns opposite narrow patterns tend to be phrased negatively ("is not [property]").

See keywords left-narrow and right-narrow.

Adjacent-numbered pages:
BP825 BP826 BP827 BP828 BP829  *  BP831 BP832 BP833 BP834 BP835

dual, handed, leftright, meta (see left/right), miniproblems, contributepairs, viceversa, presentationinvariant

boxes_bpimage_three_per_side [smaller | same | bigger]

Aaron David Fairbanks

See also BP957 for the other two evident possibilities.

Adjacent-numbered pages:
BP950 BP951 BP952 BP953 BP954  *  BP956 BP957 BP958 BP959 BP960

abstract, dual, handed, leftright, solved, meta (see left/right), miniproblems, creativeexamples, assumesfamiliarity, structure, experimental

oblong_boxes_bpimage_sorts_both_sides_skewed [smaller | same | bigger]
zoom in left (oblong_boxes_bpimage_sorts_both_sides_left) | zoom in right (oblong_boxes_bpimage_sorts_both_sides_right)

Leo Crabbe