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BP935 Shapes have equal area vs. not so.
(edit; present; nest [left/right]; search; history)
CROSSREFS

Adjacent-numbered pages:
BP930 BP931 BP932 BP933 BP934  *  BP936 BP937 BP938 BP939 BP940

KEYWORD

nice, precise, allsorted, unstable, left-narrow, perfect, pixelperfect, unorderedpair

CONCEPT area (info | search)

WORLD

2_fill_shapes [smaller | same | bigger]

AUTHOR

Leo Crabbe

BP937 Shapes have equal perimeter vs. not so.
(edit; present; nest [left/right]; search; history)
CROSSREFS

Adjacent-numbered pages:
BP932 BP933 BP934 BP935 BP936  *  BP938 BP939 BP940 BP941 BP942

KEYWORD

precise, allsorted, unstable, left-narrow, perfect, unorderedpair

CONCEPT perimeter (info | search)

WORLD

2_fill_shapes [smaller | same | bigger]

AUTHOR

Leo Crabbe

BP949 Two unique distances between points vs. three unique distances between points.
(edit; present; nest [left/right]; search; history)
CROSSREFS

Adjacent-numbered pages:
BP944 BP945 BP946 BP947 BP948  *  BP950 BP951 BP952 BP953 BP954

KEYWORD

nice, precise, allsorted, stretch, perfect, traditional, preciseworld

CONCEPT two (info | search),
three (info | search)

WORLD

3_or_4_points [smaller | same | bigger]

AUTHOR

Leo Crabbe

BP961 Includes itself on the left vs. includes itself on the right.
(edit; present; nest [left/right]; search; history)
COMMENTS

Some examples are Bongard Problems with this solution.

CROSSREFS

Adjacent-numbered pages:
BP956 BP957 BP958 BP959 BP960  *  BP962 BP963 BP964 BP965 BP966

KEYWORD

nice, precise, dual, handed, leftright, perfect, infinitedetail, both, neither, preciseworld

CONCEPT fractal (info | search),
recursion (info | search),
self-reference (info | search)

AUTHOR

Aaron David Fairbanks

BP965 If you place the image on top of itself so that it lines up with itself exactly within a small region, it also lines up everywhere else vs. not so.
(edit; present; nest [left/right]; search; history)
COMMENTS

Rotations are allowed. To avoid confusion about whether reflections are allowed, no examples are included on the right that require reflections to match up with themselves locally but not globally; no examples are included on the left that can match up with themselves locally but not globally using a reflection.


Only parts of ellipses are used, and only one type of ellipse per image, to make everything easier to read and reason about.

CROSSREFS

See BP1246 for a variation on this idea where instead of lining the image up with itself along arbitrarily small regions, you line the image up with itself along individual separate objects.

Adjacent-numbered pages:
BP960 BP961 BP962 BP963 BP964  *  BP966 BP967 BP968 BP969 BP970

KEYWORD

hard, precise, distractingworld, perfect

CONCEPT local_global (info | search)

AUTHOR

Aaron David Fairbanks

BP966 Even number of white regions vs. odd number of white regions.
(edit; present; nest [left/right]; search; history)
COMMENTS

See BP889 for the version in which the background doesn't count.

CROSSREFS

Adjacent-numbered pages:
BP961 BP962 BP963 BP964 BP965  *  BP967 BP968 BP969 BP970 BP971

KEYWORD

nice, boundingbox, number, right-null, perfect, pixelperfect, traditional, bordercontent

CONCEPT separated_regions (info | search),
even_odd (info | search)

AUTHOR

Aaron David Fairbanks

BP990 The center of mass can "see" (in straight lines) all points within the shape vs. the center of mass is not located in a region where it can see (in straight lines) all points.
(edit; present; nest [left/right]; search; history)
COMMENTS

Another way of thinking about the solution is considering whether a light source placed at the center of mass of a given example would illuminate the whole shape.

CROSSREFS

Every left for this Problem would be will be a left example for both BP367 and BP368.

Adjacent-numbered pages:
BP985 BP986 BP987 BP988 BP989  *  BP991 BP992 BP993 BP994 BP995

KEYWORD

convoluted, perfect

CONCEPT inside (info | search),
center_of_mass (info | search),
imagined_point (info | search),
imagined_line_or_curve (info | search),
imagined_entity (info | search)

WORLD

fill_shape_seeing_point_center_of_mass_inside [smaller | same | bigger]

AUTHOR

Leo Crabbe

BP991 Can be arranged with multiple copies of itself to form some convex shape vs. not so.
(edit; present; nest [left/right]; search; history)
CROSSREFS

This is a generalization of BP820.

Adjacent-numbered pages:
BP986 BP987 BP988 BP989 BP990  *  BP992 BP993 BP994 BP995 BP996

KEYWORD

precise, allsorted, perfect

CONCEPT tiling (info | search)

WORLD

fill_shape [smaller | same | bigger]
zoom in left

AUTHOR

Leo Crabbe

BP992 Concave shapes with concave cavities vs. convex cavities
(edit; present; nest [left/right]; search; history)
COMMENTS

All examples in this Problem are solid concave black shapes. In this Problem, the "cavities" of a concave shape are defined to be the convex hull of the shape minus the shape itself. For example, if you take a bite out of the edge of a piece of paper, the piece of paper in your mouth is the cavity of the bitten piece of paper. The idea may be indefinitely extended, considering whether the cavities of the cavities are concave or convex, and so on.

CROSSREFS

Adjacent-numbered pages:
BP987 BP988 BP989 BP990 BP991  *  BP993 BP994 BP995 BP996 BP997

KEYWORD

nice, precise, perfect, traditional

CONCEPT recursion_number (info | search),
recursion (info | search)

WORLD

concave_fill_shape [smaller | same | bigger]

AUTHOR

Jago Collins

BP993 Net corresponds do a unique solid vs. net can be folded into multiple different solids.
(edit; present; nest [left/right]; search; history)
COMMENTS

Right-sorted examples are called common nets.

CROSSREFS

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

Adjacent-numbered pages:
BP988 BP989 BP990 BP991 BP992  *  BP994 BP995 BP996 BP997 BP998

KEYWORD

stub, precise, 3d, perfect, preciseworld

CONCEPT rigidity (info | search),
3d_net (info | search),
3d_solid (info | search),
convey_enough_information (info | search)

WORLD

polyhedron_net [smaller | same | bigger]
zoom in left (polyhedron_net_unique_solid)

AUTHOR

Leo Crabbe

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