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Sep
4 |
awarded | Yearling |
Aug
19 |
awarded | Popular Question |
Jun
22 |
answered | Brun's algorithm |
Feb
17 |
comment |
Spectrum of primitive nonnegative integer matrices
Right now the best I can do is to enumerate all the matrices (using the trace constraint) and test them one by one... Can anyone think of a less stupid approach? |
Feb
17 |
comment |
Spectrum of primitive nonnegative integer matrices
Gerry, I haven't looked at it for hours but it doesn't seem to be obvious even for $2\times2$ matrices. |
Feb
17 |
comment |
Spectrum of primitive nonnegative integer matrices
David, unfortunately I would like to avoid the additional zero eigenvalues. Is this question open even without the primitivity assumption? Thanks for the very interesting articles! |
Feb
16 |
asked | Spectrum of primitive nonnegative integer matrices |
Feb
17 |
comment |
What are the most attractive Turing undecidable problems in mathematics?
Note the recent preprint arxiv.org/abs/1312.6700 which improves these results. Undecidability now holds for five 3*3 matrices or two 15*15 matrices. |
Jun
14 |
awarded | Nice Answer |
May
27 |
awarded | Notable Question |
Oct
20 |
awarded | Yearling |
Jul
9 |
awarded | Good Answer |
Apr
29 |
answered | Equivalent subshifts |
Apr
18 |
revised |
What's the difference between 2 and 3?
added 332 characters in body |
Apr
18 |
answered | What's the difference between 2 and 3? |
Mar
22 |
comment |
Importance of Poincaré recurrence theorem? Any example?
The ergodic theorems can be seen as improvements of the Poincaré recurrence theorem, because they relate the time average with the space average. However, the Poincaré theorem is treated first because it is not hard to prove and it is very nice. |
Mar
3 |
answered | Computational software in Algebraic Topology? |
Dec
5 |
answered | More open problems |
Oct
20 |
awarded | Yearling |
Sep
21 |
comment |
Lecture notes by Thurston on tiling
I got the above PDF version from Shigeki Akiyama and I am very glad that putting it on my website is useful to some people. It would be great if more people did this because trying to find a paper that is neither on the internet or in libraries can be extremely frustrating! |