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3 votes
1 answer
99 views

Why is the Vietoris–Rips complex $\operatorname{VR}(S, \epsilon)$ a subset of the Čech complex $\operatorname{Čech}(S, \epsilon\sqrt{2})$?

$\DeclareMathOperator\Cech{Čech}\DeclareMathOperator\VR{VR}$I am reading Fasy, Lecci, Rinaldo, Wasserman, Balakrishnan, and Singh - Confidence sets for persistence diagrams (see here for a version of ...
Kindness Chen's user avatar
1 vote
1 answer
93 views

Algorithm to find largest planar section of a convex polyhedral solid

We add a bit more on shadows and planar sections following On a pair of solids with both corresponding maximal planar sections and shadows having equal area . We consider only polyhedrons. Given a ...
Nandakumar R's user avatar
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1 vote
1 answer
128 views

An algorithm to arrange max number of copies of a polygon around and touching another polygon

A related post: To place copies of a planar convex region such that number of 'contacts' among them is maximized Basic question: Given two convex polygonal regions P and Q, to arrange the max ...
Nandakumar R's user avatar
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1 vote
0 answers
111 views

Inside-out dissections of solids -2

We record some general questions based on Inside-out dissections of solids Inside-out dissections of a cube Can every convex polyhedral solid be inside-out dissected to a congruent polyhedral solid?...
Nandakumar R's user avatar
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1 vote
0 answers
84 views

Inside-out dissections of a cube

Ref: Inside-out polygonal dissections Inside-out dissections of solids Definitions: A polygon P has an inside-out dissection into another polygon P' if P′ is congruent to P, and the perimeter of P ...
Nandakumar R's user avatar
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5 votes
1 answer
251 views

Is the maximal packing density of identical circles in a circle always an algebraic number?

There is a lot of interest in the maximal density of equal circle packing in a circle. And I thought that knowing whether or not the solution is always algebraic or not would be useful. My original ...
Teg Louis's user avatar
1 vote
1 answer
99 views

Finding the point within a convex n-gon that minimizes the largest angle subtended there by an edge of the n-gon

This post records a variant to the question asked in this post: Finding the point within a convex n-gon that maximizes the least angle subtended there by an edge of the n-gon Given a convex n-gon, ...
Nandakumar R's user avatar
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6 votes
2 answers
179 views

Finding the point within a convex n-gon that maximizes the least angle subtended there by an edge of the n-gon

For any point P in the interior of a convex polygon, the sum of the angles subtended by the edges of the polygon is obviously 2π. Given a convex polygon, how does one algorithmically find the point (...
Nandakumar R's user avatar
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1 vote
0 answers
91 views

An algorithm to decide whether a convex polygon can be cut into 2 mutually congruent pieces

This post is based on the answer to this question: A claim on partitioning a convex planar region into congruent pieces A perfect congruent partition of a planar region is a partition of it with no ...
Nandakumar R's user avatar
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1 vote
1 answer
61 views

To maximize the volume of the polyhedron resulting from perimeter-halvings of a convex polygonal region

We add one more bit to Forming paper bags that can 'trap' 3D regions of max surface area (note: some possibly open related questions are also in the comments following the answer to above ...
Nandakumar R's user avatar
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1 vote
0 answers
90 views

A claim on the largest area circular segment that can be drawn inside a planar convex region

This post adds a little to To find the longest circular arc that can lie inside a given convex polygon A circular segment is formed by a chord of a circle and the line segment connecting its endpoints....
Nandakumar R's user avatar
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0 votes
0 answers
62 views

Comparing partitions of a given planar convex region into pieces with equal perimeter and pieces of equal width

We continue from Cutting convex regions into equal diameter and equal least width pieces. There we had asked for algorithms to partition a planar convex polygon into (1) $n$ convex pieces of equal ...
Nandakumar R's user avatar
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1 vote
0 answers
81 views

Dissection of polygons into triangles with least number of intermediate pieces

This wiki article: https://en.wikipedia.org/wiki/Wallace%E2%80%93Bolyai%E2%80%93Gerwien_theorem shows the dissection of a square into a triangle via 4 intermediate pieces. It appears easy to form a ...
Nandakumar R's user avatar
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1 vote
0 answers
41 views

Are there rectangles that can be cut into non-right triangles that are pair-wise similar and pair-wise non-congruent?

We generalize the questions of Can a square be cut into non-right triangles that are mutually similar and pair-wise noncongruent? Can any rectangle be cut into some finite number of triangles that ...
Nandakumar R's user avatar
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1 vote
0 answers
92 views

Can a square be cut into non-right triangles that are mutually similar and pair-wise noncongruent?

We add a bit to Tiling the plane with pair-wise non-congruent and mutually similar triangles and Cutting polygons into mutually similar and non-congruent pieces A (non square) rectangle can obviously ...
Nandakumar R's user avatar
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