42,110 reputation
274317
bio website cs.smith.edu/~orourke
location Smith College, U.S.
age
visits member for 3 years, 11 months
seen 1 min ago
Professor of Computer Science; Professor of Mathematics.

5h
revised What was the Question that led Euler to his Investigations on Polyhedra?
Joe M.'s quote.
9h
awarded  Nice Answer
15h
comment Diameter of $n$-unit-vector closed scribble
@guest: Invented myself, in ignorance of the literature. :-)
15h
revised Diameter of $n$-unit-vector closed scribble
Responding to guest's reasonable query.
15h
comment Diameter of $n$-unit-vector closed scribble
@guest: Good question! Maybe I should answer directly in the post...
16h
asked Diameter of $n$-unit-vector closed scribble
17h
comment What is the Essential Reason that allows a PTAS for the EUCLIDEAN TSP?
And note that Mitchell independently discovered (about the same time) a PTAS for TSP, based on his guillotine subdivisions: "Guillotine Subdivisions Approximate Polygonal Subdivisions: A Simple Polynomial-Time Approximation Scheme for Geometric TSP, k-MST, and Related Problems." I cannot myself summarize to what extent his algorithm relies on the Euclidean metric.
18h
revised What was the Question that led Euler to his Investigations on Polyhedra?
Clarified that what I posted is an image, not searchable text.
21h
revised What was the Question that led Euler to his Investigations on Polyhedra?
added 14 characters in body
21h
comment What was the Question that led Euler to his Investigations on Polyhedra?
@TheMaskedAvenger: There is no caption, but, Yes, that is Cauchy. See this bio (link), which includes the same picture.
22h
answered What was the Question that led Euler to his Investigations on Polyhedra?
23h
answered Is the diameter of a centrally symmetric convex body realized by a pair of antipodal points?
1d
comment What is the best lower bound for 3-sunflowers?
Does the $C$ in $A_i \cap A_j = C$ have anything to do with $C_t$? I assume $C$ is a set. Or did you mean $|A_i \cap A_j| = C$ with $C \in \mathbb{N}$?
2d
comment Is there a sideways-walking rolling convex body?
@JoelDavidHamkins: Perhaps I should modify the question to require the initial vector of motion to be straight down $y$---roughly as in the drawn contact path. This would exclude the cylinder and many other examples.
2d
comment Is there a sideways-walking rolling convex body?
@JoelDavidHamkins: I meant composed of a uniform material, i.e., not like loaded dice, with one interior portion including more dense material than another interior portion.
2d
comment Is there a sideways-walking rolling convex body?
@JoelDavidHamkins: I don't see how to alter the question to exclude the cylinder, but that is not what I meant. :-) What I sought you found at MoMath. Thanks!
2d
accepted Is there a sideways-walking rolling convex body?
2d
asked Is there a sideways-walking rolling convex body?
Apr
16
comment Tomography problem involving a set of point masses
For points in $\mathbb{R}^3$, a version of the problem is called "shape from shadows," and is heavily studied. E.g., "The Episolar Constraint: Monocular Shape from Shadow Correspondence" PDF download link
Apr
15
accepted Limit of distance between two random points in a unit-radius $n$-sphere