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Apr
18
comment How to prove that $\binom{X+L-1}{L-1} \ge (X-L\times N)^{L-1}$?
Take $X = 0$ to get a counterexample when $L$ is odd
Mar
28
awarded  Popular Question
Jan
23
answered If $\mathbb{RP}^n$ can be immersed in $\mathbb{R}^{n+1}$, how do I see that $n$ must be of the form $2^r - 1$ or $2^r - 2$?
Jan
18
revised Find all triples of non-negative Integers $a,b,c$ such that $a!b!=a!+b!+c!$
deleted 7 characters in body
Jan
18
answered Find all triples of non-negative Integers $a,b,c$ such that $a!b!=a!+b!+c!$
Jan
16
awarded  Yearling
Jan
14
comment A subset of $[0,1]\times[0,1]$ containing at most one point from each horizontal and vertical section whose boundary is $[0,1]\times[0,1]$
the map $\pi: \mathbb{R}^{2} \to [0,1)\times [0,1)$ by $\pi(x,y) = (\{x\},\{y\}).$
Jan
13
answered Determinant of the following $(n\times n)$ matrix
Jan
13
answered How to proof that two lines in cube are perpendicular, without use of vectors
Jan
13
comment A subset of $[0,1]\times[0,1]$ containing at most one point from each horizontal and vertical section whose boundary is $[0,1]\times[0,1]$
You really only need to show that the projection of a line with irrational slope is dense in the unit square, which follows from a standard argument.
Jan
13
answered Finding the number of sequences with $0 \leq a_m \leq 3m$
Jan
13
comment Geometrical proof by induction
gave a proof, then looked at answers; since David seems to have chosen explicitly not to give a full solution, I removed mine
Jan
8
comment Tiling a Rectangle with integer length horizontal/vertical strips
@JMoravitz - Yes, I've seen this result before and the article you linked, but I'm not sure how it would help. Thanks, though
Jan
8
comment Tiling a Rectangle with integer length horizontal/vertical strips
@ArchisWelankar - no, it holds in any case.
Jan
8
asked Tiling a Rectangle with integer length horizontal/vertical strips
Jun
22
revised Diagonals of $2n$-gon bisecting area implies?
edited tags
Jun
21
asked Diagonals of $2n$-gon bisecting area implies?
Jun
18
awarded  Tumbleweed
Jun
17
comment Fundamental polygon square $abab$
He identified all of the vertices here, though, so it should only have one vertex. Also I lied about the homology; it has the same homology as that of the klein bottle
Jun
17
comment Fundamental polygon square $abab$
you could look at the euler characteristic, which is zero, so if it's actually a surface, then it would be either the klein bottle or torus. unless i'm mistaken, calculating the homology (using the cellular boundary maps) makes it clear that this isn't the case, so it's not a surface.