Intereting Posts

Do limits of sequences of sets come from a topology?
Isometry group of a norm is always contained in some Isometry group of an inner product?
How can we show that 3-dimensional matching $\le_p$ exact cover?
Given an invariant distribution is the (finite state) Markov transition matrix unique?
Multiplicative Order of $b \pmod p$ , where $p \equiv 1 \pmod 4$
if $\int_1^\infty f(x)dx$ exist, then $\int_1^\infty f^2(x)dx$ exist?
Can any meromorphic function be represented as a product of zeroes and poles?
“Empirical” entropy.
$i^{-1} F$ a sheaf if and only if $\varinjlim_{ U \subseteq X \text{ open}, ~ x,y \in U } F(U) \to F_x \times F_y$ is an isomorphism.
$\int_0^tB_s^2\ dB_s$ – Gaussian Process and independent increments?
For what $n$ is $U_n$ cyclic?
The Duplication Formula for the Gamma Function by logarithmic derivatives.
Square root confusion?
Help with graph induction proof
An introductory textbook on functional analysis and operator theory

Prompted by the question What regular polygons can be constructed on the points of a regular orthogonal grid?:

A regular octagon can be approximated on a quad lattice (grid) to about $1\text{%}$ error by knowing that the length of the diagonal of a square is $\sqrt{2}$ (~$1.414$) times as long as its side. With that information we can draw a “regular” octagon by marking the four lattice points 7 orthogonal lengths from a center point and marking the four lattice points 5 diagonal lengths from the same center point.

Is there a general rule that can be applied to create close approximations of other regular polygons on a quad-lattice (triangle, pentagon, enneagon, decagon, dodecagon, etc.)?

- Sum of Angles in a Triangle.
- Visual Ways to Remember Cross products of Unit vectors? Cross-product in $\mathbb F^3$?
- Complex Numbers Geometry
- Detecting polygon self intersection
- Intuitive meaning of immersion and submersion
- How to find the largest rectangle inside an ellipse

- Methods for showing three points in $\mathbb{R}^2$ are colinear (or not)
- About the Riemann surface associated to an analytic germ
- Equilateral triangle whose vertices are lattice points?
- Intersection of ellipse with circle
- Detecting polygon self intersection
- Partition the points
- For a general plane, what is the parametric equation for a circle laying in the plane
- Projecting a nonnegative vector onto the simplex
- Construction of a right triangle
- Height of Cylinder inscribed in Sphere

- Co-countable Topology On Uncountable Set
- Prove that $6p$ is always a divisor of $ab^{p} – ba^{p}$.
- The mapping cylinder of CW complex
- $\exists\text{ set }X:X=X^X$?
- Prime numbers divide an element from a set
- Can commuting matrices $X,Y$ always be written as polynomials of some matrix $A$?
- If $\gcd(a,b)=1$ and $\gcd(a,c)=1$, then $\gcd(a,bc)=1$
- Does the law of the excluded middle imply the existence of “intangibles”?
- Closed form of $\ln^n \tan x\, dx$
- Number of conjugacy classes of the reflection in $D_n$.
- Independence of a function and integral of a function
- Convex set of derivatives implies mean value theorem
- Which theorem did Poincaré prove?
- Linear functional $f$ is continuous at $x_0=0$ if and only if $f$ is continuous $\forall x\in X$?
- Intuition behind curl identity