10,362 reputation
2248
bio website vyznev.net
location Helsinki, Finland
age
visits member for 3 years, 4 months
seen 4 hours ago

I'm a PhD student in biomathematics, working on stochastic individual-based models of evolution in spatially structured populations. My other interests include cryptography, programming games and puzzles, photography and graphic design.

I started programming (in AmigaBASIC) when I was 10 years old. Nowadays, I'm most comfortable using Perl, C and JavaScript. I know Java and PHP too, but I can't really say I like them. I also know some Python, but not as much as I'd like.


CC-Zero Please consider any (original) code I post to Stack Overflow and other Stack Exchange sites to be released under CC-Zero unless stated otherwise. You may do whatever you want with it and don't have to credit me in any way, although of course that would be nice.


I'm the main author and maintainer of the Stack Overflow Unofficial Patch (SOUP), a user script for browsers with GreaseMonkey-compatible user script support (Firefox, Chrome, Opera, possibly Safari) that fixes or works around a number of outstanding issues with the Stack Exchange user interface.

I tend to answer a lot more questions than I ask. Some answers I'm rather proud of:


5h
comment Place two Bishops on chessboard
And the part you're having problems with is...?
23h
reviewed Approve suggested edit on Safe with $12 \times 10^6$ combinations? How is it possible?
1d
comment Does this weird sequence have a limit?
@Javier: Just to answer an old question, no it doesn't. If the real-valued sequence converged to some $x \in \mathbb R$, then for any $\epsilon>0$, there would have to be some $k_0$ such that, for all $k>k_0$, $a_k\in[x-\epsilon,x+\epsilon]$. As long as we can choose an $\epsilon>0$ such that each $a_k$ has a non-zero probability of not belonging to $[x-\epsilon,x+\epsilon]$ (i.e. as long as the probability distribution is not concentrated at $x$), the conclusion still follows.
1d
comment Is a dense subset of the plane always dense in some line segment?
@Asaf: I know this is a very old post, but since you said you'd get back to it... Anyway, I went over it again, and I'm fairly sure there's no DC (or even ACω) used here: all the choices that need to be made are from sets of the form $[a, b) \setminus \{x_1, x_2, \dotsc, x_n\}$, and the lemma above singles out a specific element $x = (x_1 + x_2)/2$ for each such set.
1d
comment What is the average of no numbers?
Under IEEE 754, the result of $\dfrac{\pm0}{\pm0}$ is $\rm NaN$, not $\pm\infty$.
1d
comment What is the average of no numbers?
Like Joe above, I do agree that, if you have to pick a real number to represent the average of no numbers, 0 is (at least) as good a choice as any. What I do genuinely wonder is what argument you have for declaring it the "only sane choice." Is there some kind of a limit argument (of weighted means?), does it make some useful lemma regarding averages hold also for the average of no numbers, or does it at least simplify some practical formulas if one defines it that way?
Aug
25
revised Limit of a rational function
use display math
Aug
22
comment What is the expected value of the number of circles formed?
@TonioElGringo: True, but expected values of dependent events are still additive.
Aug
19
revised How does exponentiation relate to multiplication?
fix b->e per comments, improve formatting
Aug
18
comment System of non-linear equations.
@DavidH: As a corollary to your rule of thumb, any exponents or other constants matching the current year also strongly suggest that the problem may be from a recent or ongoing math contest or a take-home exam.
Aug
10
revised Is there a basic “unit” of measurement in math
this sentence missing a verb
Aug
10
comment Is there a basic “unit” of measurement in math
@PaulManta: Presumably, he's referring to the quaternions and the octonions (although I've usually seen the quaternions denoted by $\mathbb H$, not $\mathbb E$).
Aug
9
revised Prove that the sequence with $T(0)=1$ and $T(n) = 1 + \sum_{j=0}^{n-1}T(j)$ is given by $T(n)=2^n$
well, let's fix it, then
Aug
9
revised A finite group of order $n$, having a subgroup of order $k$ for each divisor $k$ of $n$, is not simple?
remove deprecated [homework] tag; copy title to body text, misc. copyedits
Aug
9
revised Example of uniform convergence
remove deprecated [homework] tag
Aug
9
reviewed Edit suggested edit on Show that the limit of the function does not exist at $x \neq 0 $
Aug
9
revised Show that the limit of the function does not exist at $x \neq 0 $
Fix typo in the definition of f; remove deprecated [homework] tag
Aug
7
comment What's wrong with this proof of the infinity of primes?
While I love the Fundamental Theorem of Arithmetic, and will often use it even where weaker results (like Euclid's lemma) would do, I can't help but feel that (even if your proof were otherwise correct) using the FTA to prove the infinitude of primes would be begging the question.
Aug
2
comment Verify combinatoric argumentation.
Yes, your argument is correct.
Aug
2
revised Verify combinatoric argumentation.
fix transposed digits