121 reputation
25
bio website
location Reykjavik, Iceland
age 39
visits member for 5 years, 1 month
seen Apr 12 '10 at 12:43
Post-doctoral researcher at Reykjavik University

Sep
24
awarded  Autobiographer
Mar
8
awarded  Good Answer
Feb
10
awarded  Enthusiast
Oct
24
awarded  Nice Answer
Oct
23
answered Most helpful math resources on the web
Oct
23
comment Dyck paths on rectangles
No? Take the rectangle, rotate it 45 degrees clockwise so that the diagonal becomes the x-axis, then reflect it in the x-axis.
Oct
23
comment Placing checkers with some restrictions
Ah, yes. It can probably be fixed, somehow.
Oct
23
answered Dyck paths on rectangles
Oct
23
awarded  Editor
Oct
23
revised Placing checkers with some restrictions
Added a sketch of the bijection
Oct
22
answered Placing checkers with some restrictions
Oct
22
answered why is it so cool to square numbers? (in terms of finding the standard deviation)
Oct
22
comment why is it so cool to square numbers? (in terms of finding the standard deviation)
Ilya seems to have confused variance and standard deviation. The variance of the sum of independent random variables is the sum of the variances: Var(X+Y)=Var(X)+Var(Y) so StdDev(X+Y)=sqrt(Var(X)+Var(Y)), which in general is not equal to StdDev(X)+StdDev(Y)
Oct
21
awarded  Supporter
Oct
21
comment Pairs of shortest paths
See David Speyer's answer, who was actually worked through the details!
Oct
21
awarded  Teacher
Oct
21
answered Pairs of shortest paths