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

"Unwordable" does not just mean convoluted, that is, involving a long description. "Unwordable" also does not just mean hard. Unwordable Bongard Problems are instead those Bongard Problems whose solutions tend to occur to people nonverbally before verbally. The typical "unwordable" Bongard Problem solution is not too difficult to see, and may be easy to describe vaguely, but hard to pin down in language.

The solution title given on the OEBP for "unwordable" pages is often something vague and evocative, further elaborated on in the comments. For example, the title for BP524 is "Same objects are shown lined up in both 'universes' vs. the two 'universes' are not aligned." If someone said this, it would be clear they had seen the answer, even though this is not a clear description.

Bongard Problems have been sorted here based on how hard they are to put into words in English. (See keyword culture.) It may be interesting to consider whether or not the same choices would be made with respect to other languages.

Adjacent-numbered pages:
BP501 BP502 BP503 BP504 BP505  *  BP507 BP508 BP509 BP510 BP511

notso, subjective, meta (see left/right), links, keyword, sideless

bp [smaller | same | bigger]

Aaron David Fairbanks

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

An "overriddensolution" is solution idea for a Bongard Problem that would not be chosen by the solver because there is a simpler solution that always comes with it.

An overridden solution occurs when the Bongard Problem's examples on both sides all share some constraint, and furthermore within this constrained class of examples, the intended rule is equivalent to a simpler rule that can be understood without noticing the constraint. See e.g. BP1146. The solver of the Bongard Problem will get the solution before noticing the constraint.

There is a more extreme class of overridden solution: not only is the solution possible to overlook in favor of something simpler, but even with scrutiny it will likely never be recognized. See e.g. BP570. This happens when intended left and right side rules are not direct negations of one another, but one or both of these rules is not "narrow"-- it can only be communicated in a Bongard Problem by its opposite being on the other side.

TO DO: Should this more extreme version have its own keyword? - Aaron David Fairbanks, Nov 23 2021

The keyword left-narrow (resp. right-narrow) is for Bongard Problems whose left-side (resp. right-side) rule can be recognized alone without examples on the other side.

The keyword notso is for Bongard Problems whose two sides are direct negations of one another.

See keyword impossible for solution ideas that cannot even apply to any set of examples, much less be communicated as the best solution.

Adjacent-numbered pages:
BP563 BP564 BP565 BP566 BP567  *  BP569 BP570 BP571 BP572 BP573

BP570 "Shape outlines that aren't triangles vs. black shapes that aren't squares" was created as an example of this.

meta (see left/right), links, keyword

bp [smaller | same | bigger]

Aaron David Fairbanks

Adjacent-numbered pages:
BP633 BP634 BP635 BP636 BP637  *  BP639 BP640 BP641 BP642 BP643

meta (see left/right), links, metaconcept

bp [smaller | same | bigger]

Harry E. Foundalis

Adjacent-numbered pages:
BP682 BP683 BP684 BP685 BP686  *  BP688 BP689 BP690 BP691 BP692

meta (see left/right), links, metaconcept, primitive, left-it, feedback

bp [smaller | same | bigger]

Harry E. Foundalis

Adjacent-numbered pages:
BP686 BP687 BP688 BP689 BP690  *  BP692 BP693 BP694 BP695 BP696

meta (see left/right), links, metaconcept, primitive, left-it, feedback

bp [smaller | same | bigger]

Harry E. Foundalis

"Tiling" is placing shapes next to each other without overlap to fill up space or other shapes.

See BP835 for the version with pictures of Bongard Problems instead of links to pages on the OEBP.

Adjacent-numbered pages:
BP701 BP702 BP703 BP704 BP705  *  BP707 BP708 BP709 BP710 BP711

meta (see left/right), links, metaconcept

bp [smaller | same | bigger]

Harry E. Foundalis

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

Right examples have the keyword "ignoreimperfections".

Consider the difference in style between BP344 and BP24.

Hand-drawn figures in BPs are typically imperfect. A "circles vs. squares" BP may only show what are approximately circles and approximately squares. A pedant might append to the solutions of all Bongard Problems the caveat "...when figures are interpreted as the most obvious shapes they approximate."

This is the meaning of the label "ignoreimperfections". On the other hand, the label "perfect" means even the pedant would drop this caveat; either all the images are precise, or precision doesn't matter (see also keyword stable).

Even in BPs tagged "perfect", the tiny rough edges caused by image pixelation are not expected to matter. If the OEBP would indeed prefer users only upload pixel-perfect examples, a BP can be tagged with the stricter keyword pixelperfect.

E.g., for BPs having to do with smooth curves and lines, "perfect" only requires images offer the best possible approximation of those intended shapes given the resolution.

Most Bongard Problems involving small details at all would be tagged "perfect". However, this is not always so; sometimes the small details are intended to be noticed, but certain imperfections are still intended to be overlooked.

BP119 ("small correction results in circle vs. not") is an interesting example: imperfections matter with respect to the outline being closed, but imperfections do not matter with respect to circular-ness.

If a Bongard Problem on the OEBP is tagged "ignoreimperfections" -- i.e., it has imperfect hand drawings -- then other keywords are generally applied relative to the intended idea, a corrected version sans imperfect hand drawings. (For example, this is how the keywords precise and stable are applied. Alternative versions of these keywords, which factor in imperfect hand drawings, could be made instead, but that would be less useful.)

It may be better to change the definition of "perfect" so it only applies to Bongard Problems such that small changes can potentially switch an example's side / remove it from the Bongard Problem. That would cut down on the number of Bongard Problems to label "perfect". There isn't currently a single keyword for "small changes can potentially switch an example's side / remove it from the Bongard Problem", but this is basically captured by unstable or unstableworld. There is also deformunstable which uses a different notion of "small change". - Aaron David Fairbanks, Jun 16 2023

See BP508 for discussion of this topic in relation to Bongard Problems tagged precise.

Stable Bongard Problems are generally "perfect".

Pixelperfect implies "perfect".

The keywords proofsrequired and noproofs (BP1125) have a similar relationship: "noproofs" indicates a lenience for a certain kind of imperfection.

Adjacent-numbered pages:
BP908 BP909 BP910 BP911 BP912  *  BP914 BP915 BP916 BP917 BP918

Many Bongard Problems involving properties of curves (e.g. BP62) really are about those wiggly, imperfect curves; they qualify as "perfect" problems. On the other hand, Bongard Problems involving polygons, (e.g. BP5) often show only approximately-straight lines; they are not "perfect" problems.

Bongard Problems with world "bmp" should be "perfect".

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

visualbp [smaller | same | bigger]
zoom in left (perfect_bp)

Aaron David Fairbanks

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

Image files on the OEBP do not really have infinite detail. For a panel to be intuitively read as having infinite detail, there usually needs to be some apparent self-similarity, or perhaps a sequence of objects following an easy to read pattern getting smaller and smaller with increasing pixelation.

Usually in "infinitedetail" Bongard Problems, not only is it a puzzle to figure out the solution, but it is another puzzle to find self-similarities and understand the intended infinite detail in each example.

BPs tagged with the keyword "infinitedetail" usually feature pixelated images that give the closest approximation of the intended infinite structure up to pixelation. This means they should be tagged with the keyword perfect, but should not be tagged with the keyword pixelperfect.

Just because a Bongard Problem has "infinitedetail" does not necessarily make it infodense. Some fractal images might be encoded by a small amount of information (just the information about which places within itself it includes smaller copies of itself) and may be recognized quickly.

Adjacent-numbered pages:
BP953 BP954 BP955 BP956 BP957  *  BP959 BP960 BP961 BP962 BP963

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

visualbp [smaller | same | bigger]

Aaron David Fairbanks

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

The archetypal example is "rhombuses vs. rectangles".

Notice "rhombuses vs. rectangles" could alternatively be interpreted as "not rectangles vs. not rhombuses"; by this less natural interpretation, a square would fit on neither side (keyword neither) rather than both.

In fact, for any Bongard Problem solution "A vs. B", there are three alternative solution descriptions: "A vs. not A", "not B vs. B", and "not B vs. not A". These are not necessarily just different wordings of the same answer. For example, "rhombuses vs. not rhombuses" and "not rectangles vs. rectangles" differ on where they would sort a square. (This discrepancy between "A vs. not A" and "B vs. not B" occurs whenever "A vs. B" does not sort all relevant cases. See the keyword allsorted.)

"Is a rhombus" and "is a rectangle" are what are on the OEBP called "narrow" patterns, while "is not a rectangle" and "is not a rhombus" are not. (See keywords left-narrow and right-narrow for more explanation.)

The keywords both and allsorted are mutually exclusive.

Adjacent-numbered pages:
BP1183 BP1184 BP1185 BP1186 BP1187  *  BP1189 BP1190 BP1191 BP1192 BP1193

meta (see left/right), links, keyword

Aaron David Fairbanks

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

This is an administrative keyword to help us keep track of what Bongard Problems we still need to check for correctness.

The description should indicate which examples are still in need of checking. Once proofs are found, the keyword "missingproofs" can be removed.

The keyword noproofs is similar. The difference is whether we want/expect to find proofs.

Bongard Problems tagged "missingproofs" should necessarily be hardsort.

Adjacent-numbered pages:
BP1238 BP1239 BP1240 BP1241 BP1242  *  BP1244 BP1245 BP1246 BP1247 BP1248

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

Aaron David Fairbanks