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

Right-sorted Bongard Problems have the keyword "less." They are not necessarily "bad," but we do not want more like them.

Adjacent-numbered pages:
BP498 BP499 BP500 BP501 BP502  *  BP504 BP505 BP506 BP507 BP508

subjective, meta (see left/right), links, keyword, oebp, right-finite, left-it, feedback, time

bp [smaller | same | bigger]

Aaron David Fairbanks

Bongard Problems sorted left have the keyword "precise" on the OEBP.

Bongard Problems sorted right have the keyword "fuzzy" on the OEBP.

In an precise Bongard Problem, any relevant example is either clearly sorted left, clearly sorted right, or clearly not sorted.

(All relevant examples clearly sorted either left or right is the keyword allsorted.)

How can it be decided whether or not a rule is precise? How can it be decided whether or not a rule classifies all "examples that are relevant"? There needs to be another rule to determine which examples the original rule intends to sort. Bongard Problems by design communicate ideas without fixing that context ahead of time. The label "precise" can only mean a Bongard Problem's rule seems precise to people who see it. (This "precise vs. fuzzy" Bongard Problem is fuzzy.)

In an precise "less than ___ vs. greater than ___" Bongard Problem (keyword spectrum), the division between the sides is usually an apparent threshold. For example, there is an intuitive threshold between acute and obtuse angles (see e.g. BP292).

As a rule of thumb, do not consider imperfections of hand drawn images (keyword ignoreimperfections) when deciding whether a Bongard Problem is precise or fuzzy. Just because one can draw a square badly does not mean "triangle vs. quadrilateral" (BP6) should be labelled fuzzy; similar vagueness arises in all hand-drawn Bongard Problems. (For Bongard Problems in which fine subtleties of drawings, including small imperfections, are meant to be considered, use the keyword perfect.)

Sometimes the way a Bongard Problem would sort certain examples is an unsolved problem in mathematics. (See e.g. BP820.) There is a precise criterion that has been used to verify each sorted example fits where it fits (some kind of mathematical proof); however, where some examples fit is still unknown. Whether or not such a Bongard Problem should be labelled "precise" might be debated.

(Technical note: some properties are known to be undecidable, and sometimes the decidability itself is unknown. See https://en.wikipedia.org/wiki/Decision_problem .)

(See the keyword proofsrequired.)

One way to resolve this ambiguity is to define "precise" as meaning that once people decide where an example belongs for a reason, they will all agree about it.

Sometimes the class of all examples in a Bongard Problem is imprecise, but, despite that, the rule sorting those examples is precise. Say, for some potential new example, it is unclear whether it should be included in the Bongard Problem at all, but, if it were included, it would be clear where it should be sorted (or that it should be left unsorted). A Bongard Problem like this can still be tagged "precise".

(If all examples are clearly sorted except for some example for which it is unclear whether it belongs to the class of relevant examples, the situation becomes ambiguous.)

On the other hand, sometimes the class of all examples is very clear, with an obvious boundary. (Keyword preciseworld.)

There is a subtle distinction to draw between Bongard Problems that are precise to the people making them and Bongard Problems that are precise to the people solving them. A Bongard Problem (particularly a non-allsorted one) might be labeled "precise" on the OEBP because the description and the listed ambiguous examples explicitly forbid sorting certain border cases; however, someone looking at the Bongard Problem without access to the OEBP page containing the definition would not be aware of this. It may or may not be obvious that certain examples were intentionally left out of the Bongard Problem. A larger collection of examples may make it more clear that a particularly blatant potential border case was left out intentionally.

See BP876 for the version with pictures of Bongard Problems instead of links to pages on the OEBP.

See both and neither for specific ways an example can be classified as unsorted in an "precise" Bongard Problem.

Adjacent-numbered pages:
BP503 BP504 BP505 BP506 BP507  *  BP509 BP510 BP511 BP512 BP513

fuzzy, meta (see left/right), links, keyword, right-self, sideless

bp [smaller | same | bigger]

Aaron David Fairbanks

BPs sorted left are tagged with the keyword "abstract" on the OEBP. The solution is not an easily-checked or concretely-defined geometrical or numerical property in pictures.

Adjacent-numbered pages:
BP507 BP508 BP509 BP510 BP511  *  BP513 BP514 BP515 BP516 BP517

abstract, meta (see left/right), links, keyword, left-self, sideless

bp [smaller | same | bigger]

Aaron David Fairbanks

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

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

Experimental BPs push the boundaries of what makes Bongard Problems Bongard Problems.

Traditional BPs show some simple property of black and white pictures. The OEBP is a place with many wild and absurd Bongard Problems, so it is useful to have an easy way to just find the regular old Bongard Problems.

Adjacent-numbered pages:
BP545 BP546 BP547 BP548 BP549  *  BP551 BP552 BP553 BP554 BP555

subjective, meta (see left/right), links, keyword, left-it

bp [smaller | same | bigger]

Aaron David Fairbanks

Adjacent-numbered pages:
BP595 BP596 BP597 BP598 BP599  *  BP601 BP602 BP603 BP604 BP605

meta (see left/right), links, metaconcept, primitive

bp [smaller | same | bigger]

Harry E. Foundalis

Adjacent-numbered pages:
BP704 BP705 BP706 BP707 BP708  *  BP710 BP711 BP712 BP713 BP714

meta (see left/right), links, metaconcept, primitive

bp [smaller | same | bigger]

Harry E. Foundalis

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

Some Bongard Problems are "collective" in a more extreme way than others. Perhaps there are absolutely no individual examples that anyone would confidently sort on either side, and the solver can only be expected to get a vague gist by seeing them all together. Or perhaps in practice most people agree about where most examples should fit, even though a stretch of an argument could conceivably be made for each one fitting on the other side.

In some collective Bongard Problems, each example admits a number of possible interpretations, and the correct choice of interpretation is only clear once the solution is known. The group of examples together improve the solver's confidence about having understood each individual one right. This is common in rules Bongard Problems), where each example communicates its own rule.

Collective Bongard Problems are borderline invalid Bongard Problems (see https://www.oebp.org/invalid.php ). There is no one rule dividing the sides; the solution is not a method to determine whether an arbitrary example fits left or right. It is a less strict kind of Bongard Problem.

Collective implies fuzzy.

Collective Bongard Problems are often abstract".

Subjective Bongard Problems are often collective.

In some Bongard Problems, each example has a corresponding slightly different twin example on the other side (keyword contributepairs), and it is necessary to see both examples together in order to be able to sort either of them. This is related to "collective" but not quite the same. It becomes unambiguous where an example fits once its twin is seen.

Adjacent-numbered pages:
BP832 BP833 BP834 BP835 BP836  *  BP838 BP839 BP840 BP841 BP842

meta (see left/right), links, keyword

bp [smaller | same | bigger]

Aaron David Fairbanks

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

A most extreme "consistentsymbols" Bongard Problem is BP121: the solution is about codes consistently symbolizing objects. However, "consistentsymbols" Bongard Problems may have solution unrelated to the symbolism; the symbolism may just be implicit, e.g. always meaning dots as numbers, always meaning stacked dots as fractions, repeatedly using the same simple drawings as shorthand to represent platonic solids. Most BPs have some symbolism in this sense; a Bongard Problem should only be labelled "consistentsymbols" if there is a relatively high amount of varied symbolism, particularly if it is visual symbolism not all people would naturally understand.

A Bongard Problem featuring a real language would be another extreme example of "consistentsymbols".

A Bongard Problem with many varied images meant to be interpreted in unique ways is not necessarily "consistentsymbols," since there is no specific-to-this-Bongard-Problem vocabulary of symbols that must be known to understand it. (Even so, some might say that how people intuitively interpret images is a vocabulary on its own.)

Sometimes, the symbolism isn't an important part of the Bongard Problem, and it just helps make the Bongard Problem easier to read (see the help keyword). For example, a Bongard Problem may include many clumps of dots, and the solution of the Problem may have to do with counting the number of dots in each clump; the Bongard Problem might build up a symbolic context by always arranging each number of dots in a consistent way (e.g. how they conventionally appear on dice faces).

"Consistentsymbols" is related to the keyword structure, a format that all examples fit that the solver needs to know how to read. In "consistentsymbols" Bongard Problems, not all examples need to fit a rigid format; instead there may be various smaller structures of meaning that only appear in some examples.

"Consistentsymbols" is related to assumesfamiliarity, BPs that require the solver to take certain assumptions about what the examples are for the solution to seem simple. A "consistentsymbols" Bongard Problem may have a very convoluted solution that involves explaining the meaning of each appearing object; however, the solution can become simple given correct interpretations of all objects. This effect works best when each object must be interpreted the same way across all boxes in order for the simple solution to fit. The comments sections of "consistentsymbols" BP pages on the OEBP ought to explain the symbolism used.

Adjacent-numbered pages:
BP833 BP834 BP835 BP836 BP837  *  BP839 BP840 BP841 BP842 BP843

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

visualbp [smaller | same | bigger]

Aaron David Fairbanks

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

When this keyword is added to a Problem, OEBP users are advised to add a corresponding right example for every left example they add and vice versa.

It is common for Bongard Problems to present left examples on the left side and corresponding altered versions of those examples on the right side, tweaked only slightly, to highlight the difference and make the solution easier to see (see keyword help).

This is common in more abstract Bongard Problems that admit a wide range of examples, a variety of different styles or types (e.g. BP360). Showing two versions of the same thing, one on the left and one on the right, helps a person interpret what that thing is meant to be in the context of the Bongard Problem; whatever qualities vary between the two in the pair must be relevant.

If a person cannot sort an example according to the solution property without seeing its corresponding opposite example, the Bongard Problem is invalid (see https://www.oebp.org/invalid.php ). There is no one rule dividing the sides; the solution is not a method to determine whether an arbitrary example fits left or right. See also Bongard Problems with the keyword collective, which are similarly borderline-invalid.

A BP in which each left example corresponds to a right example and vice versa could be remade as a Bongard Problem in which the left examples are the pairs. For example BP360 would turn into "a pair consisting of the ordered version of something and the chaotic version of the same thing vs. a pair of things not satisfying this relationship." This process would turn a Bongard Problem that is invalid in the sense described above into a valid one.

(See keyword orderedpair.)

In some "contributepairs" Bongard Problems there really is a natural choice of left version for every right example and vice versa (see keyword dual); in others the choice is artificially imposed by the Bongard Problem creator.

When "contributepairs" Bongard Problems are laid out in the format with a grid of boxes on either side of a dividing line, the boxes may be arranged so as to highlight the correspondence: either

A B | A B

E F | E F

G H | G H

or

A B | B A

E F | F E

G H | H G.

Adjacent-numbered pages:
BP914 BP915 BP916 BP917 BP918  *  BP920 BP921 BP922 BP923 BP924

meta (see left/right), links, keyword, oebp, right-self, instruction

bppage [smaller | same | bigger]
zoom in left (correspondence_bp)

Aaron David Fairbanks

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

In the typical "rules" Bongard Problem, it is possible to come up with many convoluted rules that fit each example, but the intended interpretation is the only simple and obvious one.

Since it is difficult to communicate a rule with little detail, "rules" Bongard Problems are usually infodense.

Typically, each example is itself a bunch of smaller examples that all obey the rule. It is the same as how a Bongard Problems relies on many examples to communicate rules; it likely wouldn't get the answer across with just one example.

Often, each rule is communicated just by showing some examples of things satisfying it placed next to each other. (See keywords left-narrow and right-narrow.) Contrast Bongard Problems, which are more communicative, by showing some examples satisfying the rule and some examples NOT satisfying the rule.

BP1157 is an example of a "rules" Bongard Problem in which each intended rule is communicated by just one example of its application; these rules have to be particularly simple and intuitive, and the individual examples have to be complicated enough to communicate them.

A "rules" Bongard Problem is often collective. Some examples may admit multiple equally plausible rules, and the correct interpretation of each example only becomes clear once the solution is known. The group of examples together improve the solver's confidence about having understood each individual one right.

It is common that there will be one or two examples with multiple reasonable interpretations due to oversight of the author.

All meta Bongard Problems are "rules" Bongard Problems.

Many of the other Bongard-Problem-like structures seen on the OEBP are also about recognizing a pattern. (See keyword structure.)

"Rules" Bongard Problems are abstract, although the individual rules in them may not be abstract. "Rules" Bongard Problems also usually have the keyword creativeexamples.

Adjacent-numbered pages:
BP1153 BP1154 BP1155 BP1156 BP1157  *  BP1159 BP1160 BP1161 BP1162 BP1163

fuzzy, meta (see left/right), links, keyword, left-self, rules

Aaron David Fairbanks