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comment Casting out of linearly dependent vectors from a set
$S = \{ \mathbf{0} \}$ is a linearly dependent set of vectors...
Apr
14
comment bound for $\cosh$
$\cosh(1) > 1.5430$. Recheck your calculations...
Apr
13
comment Show that if $P = NP$, then deciding whether a boolean formula is minimal is in $P$.
Are you defining 'minimal' to mean 'no clause may be deleted' or 'there is no shorter formula'?
Apr
12
comment Characterization of the $x$ such that $\sin(x)$ is rational?
I suppose it's cheating to say $x = \arcsin(r)$ for some rational number $r$. :)
Apr
11
comment Where exactly is $n\log n$ between $n$ and $n^2$?
Why the downvotes?
Apr
6
comment Is the Petersen Graph k-partite?
The chromatic number of the Petersen graph is $3$.
Feb
18
reviewed Approve Linear algebra: - Linear independence and span
Feb
4
comment Is the dual graph of a planar graph an isomorphism invariant?
Wouldn't the embeddings of $K_4$ be a counterexample?
Feb
4
comment Help Figuring Out Faulty Proof
The question's purpose was not to critique or request clarification, but to indicate a portion of the 'proof' that was wrong, thus hinting to an answer of the OP's homework question.
Feb
4
comment Help Figuring Out Faulty Proof
Well you are arguing that $k^2 \leq (k+1)^2 - 1$ and that $k^2 \leq k$, but why is $(k+1)^2 - 1 \leq k$?
Feb
4
answered Help Figuring Out Faulty Proof
Jan
31
comment Evaluating $\lim_{x\rightarrow\pi}\frac{\sin x}{x^2-\pi ^2}$ without L'Hopital
$x^2 - \pi^2 = (x+\pi)(x-\pi)$
Jan
23
comment Why Do The Axioms of Euclidean Geometry Not Need To Include the Definition of Space?
Hilbert didn't define space or coordinates either, and that was a bit more recent.
Jan
23
comment Why Do The Axioms of Euclidean Geometry Not Need To Include the Definition of Space?
You are equating points with coordinates. Geometry doesn't need coordinates, so its basic axioms don't use them...
Jan
21
reviewed Approve Is the hyperbola isomorphic to the circle?
Jan
6
comment The number of e-even connected components of a graph
How many edges does a tree with $|V|$ vertices have? What is $|V|\mod 2$ and what is $eh(T)$?
Jan
6
answered The number of e-even connected components of a graph
Jan
1
comment Polygons with coincident area and perimeter centroids
You should be able to take any two polygons (rotated so their four centroid points are all collinear) and glue appropriately scaled versions together with a thin corridor so that the resulting polygon has centroids that are coincident.
Dec
29
answered Prove no odd number can be abundant.