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Jun
3
awarded  Nice Answer
May
8
answered Are There Infinitly Many $n$ Which $a\times n!+1$ Be Composite?
Apr
22
comment Create matrix containing values in [0,1] where sum of all diagonals and anti-diagonals is fixed
These conditions are always dependent, and not only due to the sum of all elements. E.g., the sum of all elements with the even sum of indices can be expressed both via $a_i$ and via $b_i$.
Apr
22
comment A digraph related to permutations
Sure, you're welcome;)
Apr
22
comment A digraph related to permutations
Each Hamiltonian path prolongates to a Hamiltonian cycle exactly for the same reason as the complete domino chain has the same numbers on both ends: a Hamiltonian cycle is an Eulerian path in a graph on the permutations of $n-1$ symbols.
Apr
8
comment Diameter of sum-graph over a non-meager set
In the first claim, a number $z$ may happen to be negative...
Apr
5
comment The diameter of a certain graph on the positive integers
Pitifully, $a$ and $a+1$ are never at distance 2.
Mar
29
answered Angle subtended by the shortest segment that bisects the area of a convex polygon
Mar
28
awarded  Nice Question
Mar
24
comment Uninteresting questions with interesting answers
Hm... When do the approximants for $\pi$ appear in such way?
Feb
23
comment Find a polynomial not in any ideal generated by polynomials of total degree $o(n)$
What if $f_1=1$?
Feb
1
comment Sets of points containing permutations - a Ramsey-type question
Still, perhaps it would be better to wait for a more sharp estimate. It is interesting to know the asymptotics of $N=N(k)$ such that in every black and white coloring of $N\times N$ square one of the colors contains every $k$-permutation. Not speaking on more colors...
Jan
31
answered Sets of points containing permutations - a Ramsey-type question
Jan
28
comment Can all unit-distance graphs have their vertices at algebraic integers?
Thanks! The link to the first one was in my answer, but I did not know about the second.
Jan
27
awarded  Nice Answer
Jan
27
comment Can all unit-distance graphs have their vertices at algebraic integers?
@David: Do you know the exact reference?
Jan
26
revised Can all unit-distance graphs have their vertices at algebraic integers?
Remark has been expanded
Jan
26
answered Can all unit-distance graphs have their vertices at algebraic integers?
Jan
26
comment Can all unit-distance graphs have their vertices at algebraic integers?
@Dima: Not much difference. A hexagonal lattice maps to $K_3$...
Jan
26
comment Irreducibility of a polynomial
Sorry, I do not understand why this question is closed.