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seen Jul 24 at 21:59

Mar
31
comment Solutions to $\binom{n}{5} = 2 \binom{m}{5}$
Considering possible values of $m$ modulo primes from 7 to 31, it's possible to quick-reject all but 8223271875 values $\pmod {247357937827}$ (i.e. to quick-reject about 29 in 30 values). It might be possible to prove that for prime $p$ at least $f(p)$ values of $m \pmod p$ have no possible value of $n \pmod p$ with a function $f$ which grows fast enough to make a heuristic argument for the number of solutions being vanishingly small.
Mar
31
comment Does there exist a closed form expression of $d_r(n,k)$?
Given that Mathworld doesn't mention a closed form expression for the simplest case, it's safe to assume that the best you can hope for is a generating function or a finite sum.
Mar
30
comment Regular expression for strings with length not a multiple of 10
What have you tried so far? (And what makes this an "interesting" problem?)
Mar
21
answered Finding almost unique sets
Mar
18
comment How does directional graph without loops but with many paths called?
Can you give an example of one which isn't a tree?
Mar
17
revised Is this star-shaped graph planar?
Add an important qualification
Mar
17
comment Is this star-shaped graph planar?
@Ryan, what I stated is (a slight misquote of - I'll correct it) Wagner's theorem, but it's closely related to Kuratowski's theorem.
Mar
16
comment Regular Languages Algorithm?
FWIW the question is badly phrased: the existence of an algorithm depends on the representation of $L$ which you are given. If you're given a DFA then yes, there is an algorithm, as Johannes has hinted. If you're given an infinite sequence of words in $L$ then there isn't an algorithm.
Mar
16
answered Is this star-shaped graph planar?
Feb
28
answered The plane $ax+by+cz=1$ contains the line $L_2$ and perpendicular to $n$. Determine $a,b,c$.
Feb
25
comment Decoding used in Algorithms
As it stands this question is rather light on context to expect a good answer. If you have the definitions then it should just be a case of working through them. If you don't, go back to the person who set the question and complain.
Feb
12
comment What is graph theory interpretation of this linear programming problem?
@Graphth, wow, thanks for the bounty! I was slightly surprised that the previous one wasn't awarded automatically, but it really wasn't necessary to do this.
Feb
11
awarded  Mortarboard
Jan
12
awarded  Yearling
Jan
6
comment Intersection point complete proof
Should we assume that the hiker makes it back to B before the end of the second day?
Jan
2
comment Petersen graph prolems
I think 4 says that the largest independent set is of size 4.
Dec
16
revised Chinese Remainder Theorem result varies
Regex bug fixed
Dec
15
comment Chinese Remainder Theorem result varies
I have sent a message through the contact page on calc2's site to notify the webmaster.
Dec
15
answered Chinese Remainder Theorem result varies
Dec
15
comment Chinese Remainder Theorem result varies
@HenningMakholm, I can reproduce the value given with calc 2.