2
votes
2answers
160 views
Question on weights and minimal degree
Edit: question has been changed from 'lexicographic' (cf. "D K"'s answer below) to 'degree' minimality.
Let $x_1,x_2,x_3$ be indeterminates. Fix an integer $k> 3$. Consider the se …
5
votes
1answer
235 views
Integer solution to special system of linear equations
This problem appear in my research, but I am unable to solve it.
There should be an easy argument, but I have not yet found it.
Informal version
An integer $k\geq 2$ is fixed.
We …
0
votes
1answer
83 views
Discretizing a cosine function?
I'd like to start by noting that for some fixed natural $N$ basis functions for my system will be generated by $f(k,x)$ as defined and explained here or in numerous other sources:
…
1
vote
1answer
137 views
How to determine the number of a cube within a bigger cube?
Hi all,
I have a cube, sized 39 x 13 x 8. I need to find out how many of them can fit in a cube of 100 x 100 x 100. I need to find the highest number possible.
Do you know of a w …
0
votes
0answers
106 views
Two variable recurrence equation with varying coefficients
Hello,
I have the following two variable recurrence equation for integers $j,k$:
$f(j,k) = (k/j)f(j-1,k-1) - (3 + k/j)f(j-1,k+2)$
where $f(j,0) = (3^j - 1)/j + 3jf(j-1,2)$, $f(0 …
2
votes
1answer
50 views
On solution of a class of discrete-time Lyapunov equation
Hello members, let's consider the following equation
$$X=F_{1}XF_{1}^{T}+...+F_{p}XF_{p}^{T}+C$$
where $p$ is an positive integer and $C$ is a known positive semidefinite matrix. I …
6
votes
3answers
273 views
References on techniques for solving equations with discontinuous functions such as floor and ceiling?
Here I describe the sort of reference I'm after with a motivating example. I am not seeking solutions to my equations on this forum; I'm quite happy to do that myself. Rather, I'm …
2
votes
1answer
73 views
On solution of a discrete-time equation
Hello, members.
I have a problem for the following problem
when I derive an optimization algorithm for stochastic singular systems
$$S(k+1)=A(k)S(k)A^{T}(k)+R(k)+F(k)S(k+1)F^{T}( …
0
votes
1answer
118 views
Distance between vertices in a vertex transitive graphs. [closed]
Can anybody help me in finding out the distances between vertices in a vertex transitive graphs. Is there any specific formula to calculate distance between vertices in this graph. …
13
votes
1answer
403 views
Does erosion mix faster than a riffle shuffle?
It is a famous result of Aldous and Diaconis1 that
seven shuffles are necessary and suffice to approximately
randomize 52 cards.2
Here the shuffles are the standard riffl …
2
votes
0answers
105 views
Citation for subset complement result
Let $S=\lbrace s_1,\ldots,s_n \rbrace \subset \lbrace1,\ldots,2n\rbrace$. Consider two operations on $S$: the complement $C(S)=\lbrace 1,\ldots,2n \rbrace \setminus S$ and a reflec …
23
votes
5answers
991 views
How many binary operations are associative?
Let $X$ be a finite set of $n$ elements, and consider a binary operation $\odot: X \times X \rightarrow X$. There are $n^{n^2}$ such binary operations, as the $n \times n$ table e …
11
votes
4answers
1k views
Has any attempt been made to classify finite groupoids?
I recently stumbled upon the Mathieu groupoid and I found them fascinating.
It appears as a subset of $S_{13}$ which is not closed under multiplication, but it turns out to be a g …
0
votes
0answers
44 views
How to use Dirichlet Prior
Regarding this question:
http://mathoverflow.net/questions/72668/how-to-compute-kl-divergence-when-pmf-contains-0s
One of the solutions requires the use of a "Dirichlet Prior", I …
4
votes
1answer
128 views
Best upper bound on rate for q-ary codes
Among the many upper bounds for families of codes in $\mathbb F _2 ^n$, the best known bound is the one by McEliece, Rodemich, Rumsey and Welch which states that the rate $R(\delta …

