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

All the possible left examples for the BPs on the left side of this problem could be listed in one infinite sequence. Right examples here are Problems for which no such sequence can exist.

This depends on deciding what images should be considered "the same thing", which is subjective and context-dependent.

All examples in this Bongard Problem have an infinite left side (they do not have the keyword left-finite).

The mathematical term for a set that can be organized into an infinite list is a "countably infinite" set, as opposed to an "uncountably infinite" set.

Another related idea is a "recursively enumerable" a.k.a. "semi-decidable" set, which is a set that a computer program could list the members of.

The keyword "left-listable" is meant to be for the more general idea of a countable set, which does not have to do with computer algorithms.

Note that this is not just BP940 (right-listable) flipped.

It seems in practice, Bongard Problems that are left-listable are usually also right-listable because the whole class of relevant examples is listable. A keyword for just plain "listable" may be more useful. Or instead keywords for left- versus right- semidecidability, in the sense of computing. - Aaron David Fairbanks, Jan 10 2023

https://en.wikipedia.org/wiki/Countable_set

See left-finite, which distinguishes between a finite left side and infinite left side.

"Left-listable" BPs are typically precise.

Adjacent-numbered pages:
BP558 BP559 BP560 BP561 BP562  *  BP564 BP565 BP566 BP567 BP568

math, meta (see left/right), links, keyword

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

Leo Crabbe

Left-sorted BPs have the keyword "left-null" on the OEBP.

Right-sorted BPs have the keyword "right-null" on the OEBP.

See BP796 for the version with pictures of Bongard Problems (miniproblems) instead of links to pages on the OEBP.

See BP1160 for the version about an all-black panel instead of all-white.

Adjacent-numbered pages:
BP562 BP563 BP564 BP565 BP566  *  BP568 BP569 BP570 BP571 BP572

meta (see left/right), links, keyword, side, wellfounded, testexample

visualbp [smaller | same | bigger]

Aaron David Fairbanks

Left examples have the keyword "solved" on the OEBP.

Right examples have the keyword "challenge" on the OEBP.

Adjacent-numbered pages:
BP821 BP822 BP823 BP824 BP825  *  BP827 BP828 BP829 BP830 BP831

meta (see left/right), links, keyword, time

Aaron David Fairbanks

Adjacent-numbered pages:
BP918 BP919 BP920 BP921 BP922  *  BP924 BP925 BP926 BP927 BP928

meta (see left/right), links, metaconcept

bp [smaller | same | bigger]

Leo Crabbe

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

BPs are sorted based on how BP563 (left-listable) would sort them were they flipped; see that page for a description.

See right-finite, which distinguishes between finite right side and infinite right side.

Adjacent-numbered pages:
BP935 BP936 BP937 BP938 BP939  *  BP941 BP942 BP943 BP944 BP945

meta (see left/right), links, keyword

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

Leo Crabbe

Left examples have the keyword "grid" on the OEBP.

Right examples have the keyword "fixedgrid" on the OEBP.

See also sequence versus fixedsequence.

Adjacent-numbered pages:
BP1171 BP1172 BP1173 BP1174 BP1175  *  BP1177 BP1178 BP1179 BP1180 BP1181

meta (see left/right), links, keyword

visualbp [smaller | same | bigger]

Leo Crabbe

Adjacent-numbered pages:
BP1172 BP1173 BP1174 BP1175 BP1176  *  BP1178 BP1179 BP1180 BP1181 BP1182

meta (see left/right), links

Leo Crabbe

Examples sorted by this problem need to be Bongard Problems with some multiple disconnected shapes in them that are formatted in some way.

Problems do not necessarily need symbols to recur across examples to be sorted left.

Right-sorted Problems usually vary their object "language" across examples to emphasise the generality of their solution. Every example in these problems would be thought of as having its own intuitive "world".

TO DO: Figure out whether to implement the prerequisite "You must easily be able to think of a way that a sorted problem could be redrawn such that its sorting in this Problem would switch." This restriction would eliminate problems like BP121 from being sorted, for example, as its solution hinges on the consistency of the symbols across examples. The keyword consistentsymbols already describes problems like this. This also eliminates problems like BP998 from sorting.

TO DO: Should this problem's world be changed from "Formatted object comparison BPs" to "object comparison BPs"? This would allow for some nice Problems like BP841 to be sorted, but may make things too broad.

Adjacent-numbered pages:
BP1173 BP1174 BP1175 BP1176 BP1177  *  BP1179 BP1180 BP1181 BP1182 BP1183

meta (see left/right), links

Leo Crabbe