The On-Line Encyclopedia of Bongard Problems

Here are some properties of Bongard Problems that we have decided are interesting enough to distinguish with an easy-to-search label.
To see all the Bongard Problems with (for example) keyword nice, type keyword:nice into the search bar.

Since this is a website based on showing properties of things in Bongard Problems, each keyword is actually a meta Bongard Problem (a Bongard Problem sorting Bongard Problems). To add a keyword to a Bongard Problem, add the Bongard Problem to the appropriate side of the Bongard Problem for that keyword.
There is also a "KEYWORDS" section in the Bongard Problem submission form, in which you can enter the names of keywords, that makes this process more convenient.

Table of keywords
Keyword	Description	Meta BP number
`easy`	Easy for people to solve.	BP501^left
`hard`	Hard for people to solve.	BP501^right
`nice`	"NP" (Nice Problem!)	BP503^left
`less`	More Bongard Problems like this should not be added to the database. It may be interesting as a one-off example or is kept for historical reasons.	BP503^right
`stub`	More examples are needed. Please add to this Bongard Problem.	BP504^left
`precise`	A Bongard Problem with an exact definition. For all possible examples, it is clear which go left, which go right, and which are uncategorized.	BP508^left
`fuzzy`	A Bongard Problem with an inexact definition.	BP508^right
`allsorted`	A Bongard Problem that sorts all possible relevant examples. There are no uncategorized cases.	BP509^left
`abstract`	The solution is not a literal geometrical or numerical property in examples.	BP512^left
`noisy`	There are extraneous details shown changing between examples that distract from the solution.	BP511^left
`minimal`	The only details shown changing between examples are those necessary to communicate the solution.	BP511^right
`convoluted`	A Bongard Problem with convoluted solution involving clauses connected by "OR"s or elaborate rules in the description. These Bongard Problems would usually also be tagged with the keyword "less."	BP549^right
`unwordable`	The solution is hard to put into words concisely. (This does not necessarily mean that the solution is hard to see.)	BP506^left
`notso`	A Bongard Problem with solution naturally expressed as "[fits rule] vs. not so."	BP867^left
`teach`	A Bongard Problem whose examples might be used to teach a person or computer to recognize the pattern.	BP858^left
`spectrum`	A Bongard Problem involving a less-than/greater-than quantity comparison.	BP507^left
`dual`	A Bongard Problem in which there is a natural one-to-one correspondence between left examples and right examples; there is some clear way to transform an example that will flip its side.	BP534^left
`arbitrary`	The solution involves something arbitrary. Changing around this arbitrary detail gives way to many slightly different Bongard Problem with equally nice solutions.	BP950^left
`handed`	A Bongard Problem in which orientation is relevant; flipping examples might affect their sorting.	BP552^left
`leftright`	A Bongard Problem in which left-right orientation is relevant; flipping examples over the vertical axis might affect their sorting.	BP535^left
`updown`	A Bongard Problem in which up-down orientation is relevant; flipping examples over the horizontal axis might affect their sorting.	BP1009^left
`rotate`	A Bongard Problem in which rotation is relevant; rotating examples might affect their sorting.	BP553^left
`size`	A Bongard Problem in which absolute size is relevant; scaling examples might affect their sorting.	BP554^left
`stretch`	A Bongard Problem in which stretching examples might affect their sorting.	BP1112^left
`boundingbox`	A Bongard Problem in which expanding the bounding boxes of examples might affect their sorting.	BP974^left
`blackwhite`	A black and white Bongard Problem in which flipping the black and white pixels in examples might affect their sorting.	BP556^left
`stable`	A Bongard Problem in which small changes to examples cannot affect their sorting.	BP963^right
`unstable`	A Bongard Problem in which small changes to examples can affect their sorting.	BP963^left
`number`	The solution only depends on counting the number of something.	BP575^right
`math`	The solution is about mathematics.	BP571^left
`physics`	The solution is related to physical phenomena.	BP572^left
`3d`	A Bongard Problem about 3D objects such that the solution is unrelated to the particular 2D representation.	BP1010^right
`projectionmatters`	A Bongard Problem about 3D objects such that the solution is related to the particular 2D representation.	BP1010^left
`hardsort`	A Bongard Problem in which some examples might be hard to sort even after the solution is known.	BP864^right
`antihuman`	A Bongard Problem that is hard for people to solve and easier for computers to solve.	BP565^left
`anticomputer`	A Bongard Problem that is hard for computers to solve and easier for humans to solve.	BP565^right
`subjective`	A Bongard Problem in which sorting examples is subjective.	BP520^left
`culture`	A Bongard Problem that involves culture-based information.	BP521^left
`solved`	Somebody has solved this hard Bongard Problem (without hints).	BP826^left
`challenge`	Nobody has solved this hard Bongard Problem (without hints).	BP826^right
`meta`	A Bongard Problem whose examples are Bongard Problems.	BP537^left
`links`	A meta Bongard Problem whose examples are links to other pages on the OEBP.	BP1126^left
`miniproblems`	A meta Bongard Problem whose examples are miniature images of Bongard Problems.	BP1126^right
`keyword`	A meta Bongard Problem corresponding to one of the keywords in this list.	BP518^left
`oebp`	A Bongard Problem with solution related to the OEBP.	BP1113^left
`example`	A Bongard Problem that was included on the OEBP primarily to be used as an example in other, meta Bongard Problems.	BP1121^left
`world`	A Bongard Problem such that one of its sides is commonly used as the pool of examples (the world) for other Bongard Problems on the OEBP.	BP546^left
`concept`	A Bongard Problem with solution "Related to [concept] vs. not so."	BP814^left
`metaconcept`	A meta Bongard Problem listing Bongard Problems related to some specific concept.	BP519^left
`primitive`	A metaconcept Bongard Problem about a property primitive to visual cognition. (See Harry E. Foundalis's work.)	BP577^left
`left-self`	A meta Bongard Problem that is sorted on its own left side. This keyword is added to pages automatically.	BP517^left
`right-self`	A meta Bongard Problem that is sorted on its own right side. This keyword is added to pages automatically.	BP517^right
`side`	A meta Bongard Problem in which flipping the sides of Bongard Problems might affect their sorting.	BP539^left
`sideless`	A meta Bongard Problem in which any Bongard Problem and its flipped version are both sorted the same way.	BP539^right
`invariance`	A meta Bongard Problem about whether a certain transformation can affect examples' sorting.	BP566^left
`creativeexamples`	A Bongard Problem in which some examples fit the solution in varied creatively interesting ways.	BP866^left
`presentationmatters`	A meta Bongard Problem that does not sort Bongard Problems based solely on their solutions.	BP895^left
`metameta`	A Bongard Problem that sorts meta Bongard Problems.	BP547^left
`metametameta`	A Bongard Problem that sorts meta meta Bongard Problems.	BP1007^left
`overriddensolution`	A solution idea that can never be communicated because a simpler solution will always override it.	BP568^left
`gap`	A Bongard Problem in which the two sides are completely different classes of examples, with no clear choice of middle-ground in between.	BP964^right
`distractingworld`	The class of examples included is irrelevant to the solution idea.	BP865^left
`animated`	A Bongard Problem that uses animation in its examples.	BP995^left
`color`	A Bongard Problem that uses color in its examples.	BP976^left
`proofsrequired`	The OEBP encourages any user uploading an example to provide a proof the example fits where they think it does.	BP1125^left
`noproofs`	It is very difficult to be sure where an example fits in this Bongard Problem; a user uploading an example does not need to have a proof the example fits where they think it does; if an error is found, the community will correct it later.	BP1125^right
`left-unknowable`	It is impossible to be sure an example fits left in this Bongard Problem. Just sort as left the examples that nobody has yet found to fit right.	BP1124^left
`right-unknowable`	It is impossible to be sure an example fits right in this Bongard Problem. Just sort as right the examples that nobody has yet found to fit left.	BP1124^right
`left-narrow`	Left examples are distinctive enough alone to communicate the answer; right examples are unnecessary.	BP513^left
`right-narrow`	Right examples are distinctive enough alone to communicate the answer; left examples are unnecessary.	BP514^left
`left-finite`	A Bongard Problem with a finite number of possible examples fitting left.	BP515^left
`right-finite`	A Bongard Problem with a finite number of possible examples fitting right.	BP516^left
`left-full`	A Bongard Problem page that intends to collect ALL left examples.	BP573^left
`right-full`	A Bongard Problem page that intends to collect ALL right examples.	BP574^left
`left-null`	A Bongard Problem that would sort a blank panel on its left side.	BP567^left
`right-null`	A Bongard Problem that world sort a blank panel on its right side.	BP567^right
`left-it`	A meta Bongard Problem that sorts the "it" Problem on its left side.	BP1073^left
`right-it`	A meta Bongard Problem that sorts the "it" Problem on its right side.	BP1073^right
`wellfounded`	A meta Bongard Problem that contains no infinite chain of meta-Bongard Problems containing meta Bongard Problems . . .	BP794^right
`feedback`	A meta Bongard Problem that contains a chain of meta-Bongard Problems containing meta Bongard Problems . . . that eventually loops back to itself.	BP1074^left
`ignoreimperfections`	A Bongard Problem with hand-drawn examples that may be slightly wrong.	BP913^right
`perfect`	A Bongard Problem that does NOT have the typical slightly-wrong hand-drawings for examples; all subtle imperfections are relevant.	BP913^left
`pixelperfect`	The OEBP prefers for users to never submit images in which the pixellation is misleading.	BP947^left
`infinitedetail`	Images are intended to be parsed as infinitely detailed structures.	BP958^left
`infodense`	Each example is tightly packed with information the solver has to unpack in order to solve the Bongard Problem.	BP978^left
`assumesfamiliarity`	A Bongard Problem requiring the solver to go in with certain expectations for the solution to seem simple.	BP1111^left
`structure`	A Bongard Problem with all examples featuring a specific multi-part structure commonly used on the OEBP, e.g. the Bongard Problem.	BP789^left
`consistentsymbols`	A Bongard Problem in which there is an intended consistent way to parse symbols shown in the examples.	BP838^left
`collective`	A Bongard Problem in which there is no clear way to sort individual examples, but together many examples are able to communicate the idea.	BP837^left
`finished`	Users should not submit any more examples to this Problem.	BP504^right
`help`	The OEBP encourages users to upload examples that are designed to hint people toward the solution.	BP930^left
`contributepairs`	The OEBP encourages users to upload left and right examples in matching pairs.	BP919^left
`instruction`	A keyword added to Bongard Problem pages to instruct OEBP users about what kinds of edits they should make to the page rather than to catalogue a property of the Bongard Problem.	BP967^right
`sequence`	A Bongard Problem about arbitrarily long sequences of objects.	BP929^left
`fixedsequence`	A Bongard Problem about sequences of objects of fixed length.	BP929^right
`unorderedpair`	A Bongard Problem about comparing two objects such that the order of the objects does not matter.	BP787^right
`orderedpair`	A Bongard Problem about comparing a first object with a second object.	BP787^left
`unorderedtriplet`	A Bongard Problem about comparing three objects such that the order of the objects does not matter.	BP908^right
`orderedtriplet`	A Bongard Problem about comparing a first object, a second object, and a third object.	BP908^left
`time`	A Bongard Problem that can change how it sorts examples over time. This probably means the Bongard Problem has cultural references.	BP510^left
`invalid`	Something that does not quite fit the definition of Bongard Problem but is interesting enough to keep in the database.	BP522^left
`impossible`	A Bongard Problem page for an idea that couldn't physically be made into a Bongard Problem.	BP821^left
`experimental`	A Bongard Problem that was created to push boundaries of what Bongard Problems are allowed to be.	BP550^left
`traditional`	A Bongard Problem featuring black and white images with a simple solution property.	BP550^right
`funny`	An amusing Bongard Problem.	BP1000^left
`blackwhiteinvariant`		BP556^right
`left-listable`		BP563^left
`bongard`		BP798^left
`presentationinvariant`		BP895^right
`right-listable`		BP940^left
`visualimagination`		BP960^left
`inductivedefinition`		BP1128^left
`finishedexamples`		BP1142^left
`continuous`		BP1152^right
`discrete`		BP1152^left
`rules`		BP1158^left
`right-couldbe`		BP1159^right
`left-couldbe`		BP1159^left
`viceversa`		BP1162^left
`problemkiller`		BP1170^left
`fixedgrid`		BP1176^right
`grid`		BP1176^left
`miniworlds`		BP1180^left
`both`		BP1188^left
`neither`		BP1189^left
`preciseworld`		BP1190^left
`absoluteposition`		BP1195^left
`bordercontent`		BP1196^left
`dithering`		BP1198^left
`stableworld`		BP1203^right
`unstableworld`		BP1203^left
`stability`		BP1204^left
`deformstable`		BP1205^right
`deformunstable`		BP1205^left
`dependence`		BP1225^left
`seemslike`		BP1231^left
`testexample`		BP1242^left
`collection`		BP1265^left

		Hints
(Greetings from The On-Line Encyclopedia of Bongard Problems!)

Keywords in the OEBP