4,478 reputation
1435
bio website
location
age
visits member for 4 years, 4 months
seen 2 days ago

Mar
5
comment Does there exist a system such that the additive identity is non-zero?
In the semiring of languages (sets of strings), union of two languages acts like addition, and the additive identity is the empty set. Multiplication is string concatenation (well a little more complicated than just that) and the multiplicative identity is the empty string.
Mar
5
comment Does there exist a system such that the additive identity is non-zero?
@Brilland: they might be tempted to call it that, but that would be misleading about the meaning of the operators. The abstract operator '⊗' acts like multiplication. The fact that it is implemented as arithmetic addition is, well not exactly irrelevant, but just not as important is the fact that it acts analogously to arithmetic multiplication.
Feb
17
reviewed Approve unlimited combination
Feb
15
answered What's the intuition behind Pythagoras' theorem?
Feb
9
reviewed Approve Find angle between two planes
Feb
9
comment combinations $\sum_{k=1}^m kn_k=m!$
Just to be clear, for example, if $m = 4$ you'd like the number of solutions of $24 = n_1 + 2 n_2 + 3 n_3 + 4 n_4$ ?
Feb
8
comment combinations $\sum_{k=1}^m kn_k=m!$
So, to put into words, you're trying to find the integer partitions of $m!$ into $m$ parts?
Feb
8
comment Find “n” using the following conditions.
My bad...I missed the '$P(x)$ is a polynomial of degree $3n$'
Feb
8
comment combinations $\sum_{k=1}^m kn_k=m!$
What is $n_k$? That's not a notation I'm familiar with if it is some function of $n$ and $k$.
Feb
8
comment Find “n” using the following conditions.
This doesn't seem possible. It looks like $P(k+3) = P(k)$, so $P(3n+1) = P(3n-2) = 1$ which is inconsistent with $P(3n+1) = 730$.
Jan
28
comment The Hexagonal Property of Pascal's Triangle
I haven't been ignoring you. I'm still thinking about all this.
Jan
26
comment We are learning about LU Decomposition .. because?
What can you use LU decomposition for? (solving a system of equations) Why can't you just invert the matrix and multiply on the other side? (you certainly can but it takes longer). Also you can do LU decomposition in-place. Which is what Amzoti's link says.
Jan
17
revised Has there been a rigorous analysis of Strassen's algorithm?
small style and emphasis rewrites.
Jan
15
reviewed Approve Small Combinatorical Question - Pigeonhole Principle Related
Jan
14
awarded  Custodian
Jan
4
awarded  Pundit
Jan
4
comment ordering 3 couples in 3 rows
Is it three friends or six?
Dec
30
comment Bijection from ordered pairs of $[0,n]$
What's wrong with the Cantor pairing function? The bijection is infinite.
Dec
30
comment How to find coefficient of $x^8$ in $\frac{1}{(x+3)(x-2)^2}$
I think the OP wants a rational, not a floating point number.
Dec
26
comment General form for the series expansion of $e$
Does this mean that $$\sum_{n=1}^{\infty} \frac{n^k}{n!} = e \cdot B(k)$$ where B(k) is the number of set partitions of $k$?