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This tag is used if a reference is needed in a paper or textbook on a specific result.

3 votes

Basic question about polytope duals

While the answer to the question of OP is "no", I would like to mention a question raised by Grünbaum and Shephard in "Some problems on polyhedra.", J. Geom. 29 (1987), no. 2, 182–190, for the informa …
Hao Chen's user avatar
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2 votes
0 answers
82 views

Are the following hyperplane arrangements previously studied?

For a subset $I$ of $[n]$, a hyperplane $H_I \subset \mathbb{R}^n$ is defined by $$\sum_{i \in I} x_i= \sum_{j \not\in I} x_j.$$ Have you seen the following hyperplane arrangements? Is there anything …
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5 votes
1 answer
793 views

Non-zero winding number on a space curve implies a linked curve in the zero set?

The following statement has been largely improved from my original post thanks to discussions with @DmitriPanov ad well as the comment from @Wojowu. Let $f \colon \mathbb{S}^3 \to \mathbb{R}^2$ be …
Hao Chen's user avatar
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7 votes
2 answers
178 views

Graph embedding that locally minimizes total edge lengths

I consider a graph $G$ (possibly infinite, but locally finite) embedded in the Euclidean plane $\mathbb{E}^2 \cup \{\infty\}$ such that each local perturbation of the embedding "increases the total le …
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6 votes

Some polytopes in $\mathbb R^n$ whose vertices have coordinates 1, -1 or 0

View the two examples, I think $P(n,k)$ is the $(n-k)$-rectified $n$-hypercube or the $(k-1)$-rectified $n$-cross-polytope (same thing). I believe the notion of rectification will be very helpful for …
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1 vote

Graph embedding that locally minimizes total edge lengths

Finally, I find that the works of Ivanov and Tuzhilin seem to be very close to what I'm looking for.
Hao Chen's user avatar
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5 votes
1 answer
266 views

Generalized Plateau problem with non-Jordan boundary

Let $C_\pm$ be the two circles obtained by intersecting the cylinder $x^2+y^2=R^2$ with the planes $z=\pm 1$, on which we mark four points $A_\pm:(R,0,\pm 1)$ and $B_\pm:(-R,0,\pm 1)$. Assume that $R …
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3 votes
0 answers
100 views

Symmetries of irregular simplices

On the wikipedia page of tetrahedron, there is a list of eight symmetry groups for a (possibly irregular) $3$-simplex (with unmarked faces). There is also a list on the page of 5-cell but doesn't see …
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7 votes
1 answer
341 views

For a 3D Apollonian packing, do we really know that the Hausdorff dimension of the complemen...

The fractal dimension of the 3D Apollonian packing is computed in this paper. In the introduction, the authors cite three of Boyd's paper (Ref 2, 5, 6) to support that the fractal dimension (Hausdo …
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1 vote
Accepted

For a 3D Apollonian packing, do we really know that the Hausdorff dimension of the complemen...

OK, I found the reference: For those who care, it's recently proved in a much stronger form by Oh and Shah in The asymptotic distribution of circles in the orbits of Kleinian groups. The paper is ab …
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17 votes
Accepted

Koebe–Andreev–Thurston theorem - where can I find a proof?

There are many proofs, and I'm not claiming that the following list is complete. New references are welcome. (First proof) Paul Koebe, Kontaktprobleme der konformen Abbildung, Ber. Verh. Sächs. Ak …
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3 votes

Is there a midsphere theorem for 4-polytopes?

I recently showed that: The graph of a stacked $4$-polytope is $3$-ball packable if and only if it does not contain six $4$-cliques sharing a $3$-clique. While Eppstein, Kuperberg and Ziegler 20 …
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5 votes

Is there a midsphere theorem for 4-polytopes?

In a recent paper of Padrol and me, we studied several generalizations of this problem. http://arxiv.org/pdf/1508.03537v1.pdf Regarding Q1, Yoav already mentioned Schulte's work, and Gil mentioned t …
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5 votes
0 answers
94 views

Is every space group the symmetry group of some triply periodic minimal surface?

I know that there are a lot of TPMS with different symmetry groups. It seems like every space group is the symmetry group of some TPMS. But I can not find a reference that confirms this for all the …
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3 votes
1 answer
142 views

Applications of maximal surfaces in Lorentz spaces

I have been working on minimal surfaces, only recently learnt about maximal surfaces and "maxfaces" in Lorentz spaces. I can clearly see the mathematical motivations. But I wonder if zero-mean-curvat …
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