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1d
revised Pach's “Animals”: What if the genus is positive?
link fixed
Oct
4
comment (non-)existence of the aperiodic monotile
Not exactly. That paper talks only about tilings of the plane with parallel traslates. These are MUCH easier than general tilings.
Sep
30
awarded  Explainer
Aug
15
awarded  Good Answer
Aug
8
comment What exact number of domino tilings cannot be realizable?
Let's say you have two integers $m<n$. Can you always find a s.c. region $G$ and a domino $D \subset G$, s.t. $G$ has exactly $n$ tilings, but $G-D$ has only $m$?
Jul
13
answered What is known about tiling a rectangle in an irreducible way by smaller rectangles?
Jun
14
answered A Simple Bijective Proof Of Stanley's Hook-Content Formula for Hook Shapes
May
6
awarded  Nice Answer
Mar
5
awarded  Enlightened
Mar
5
awarded  Nice Answer
Feb
24
awarded  Necromancer
Feb
16
awarded  Nice Answer
Feb
16
awarded  Yearling
Feb
16
answered Conjecture on NP-completeness of tesselation of Wang Tile up to finite size
Feb
14
awarded  Good Answer
Feb
11
comment How hard is it to determine if a weighted graph can be isometrically embedded in R^3?
Actually, (3) applies to non-convex triangulated spheres as well. Of course, nothing is impossible, but even for the icosahedron with slightly perturbed edge lengths, the degrees of equations are not very encouraging (between 2^10 and 2^30).
Feb
10
answered How hard is it to determine if a weighted graph can be isometrically embedded in R^3?
Jan
14
awarded  Nice Answer
Jan
14
revised Minimal generating sets of groups
copy
Jan
14
answered Minimal generating sets of groups