Intereting Posts

In what senses are archimedean places infinite?
Finding $\lim_{x\to \pm\infty}f(x)$ where $a,b>0$
self similar solution for porous medium equation 3
Measurability and almost sure convergence
Minimum distance of a binary linear code
Counting Combinations of a List of Numbers
Analytic function in the punctured plane satisfying $|f(z)| \leq \sqrt{|z|} + \frac{1}{\sqrt{z}}$ is constant
Is it possible for an irreducible polynomial with rational coefficients to have three zeros in an arithmetic progression?
Tower property of conditional expectation
Expanding a potential function via the generating function for Legendre polynomials
Avoiding the Cayley–Hamilton theorem
Series expansion for $e^{- x^2}$
Jordan decomposition of an endomorphism with minimal polynomial
How do I prove that a function with a finite number of discontinuities is Riemann integrable over some interval?
Why is there antagonism towards extended real numbers?

I have an idle curiosity about a funny coincidence between two sequences of groups. It is well-known by those who know it well that the alternating group $A_d$ of degree $d$ is simple if and only if $d\not\in\{1,2,4\}$. By what seems like an astonishing coincidence to me, the special orthogonal group $SO(d,\mathbb{R})$ is simple if and only if $d\not\in\{1,2,4\}$. Is this merely a coincidence?

- What is Abstract Algebra essentially?
- Groups with only one element of order 2
- Proving that the characters of an infinite Abelian group is a basis for the space of functions from the group to $\mathbb{C}$
- Prove that $HK$ is a subgroup iff $HK=KH$.
- $G$ be a free abelian group of rank $k$ , let $S$ be a subset of $G$ that generates $G$ then is it true that $|S| \ge k$?
- Can a free group over a set be constructed this way (without equivalence classes of words)?
- Prove that Z(G) which is the center of G is a subgroup of G
- Is there a rank 3 boolean interval with G simple group?
- How to geometrically show that there are $4$ $S_3$ subgroups in $S_4$?
- Prove where exp: Skew($3\times 3$) $\rightarrow SO(3)$ is local homeomorphism

- How can I find $\sum\limits_{n=0}^{\infty}\left(\frac{(-1)^n}{2n+1}\sum\limits_{k=0}^{2n}\frac{1}{2n+4k+3}\right)$?
- Alternative analytic continuation to zeta, not giving $-\frac{1}{12}$ for sum of integers
- What are the properties of the roots of the incomplete/finite exponential series?
- Prove that $\log X < X$ for all $X > 0$
- Good way to learn Ramsey Theory
- First-order logic and second-order logic confusion
- Prove limit of $\sum_{n=1}^\infty n/(2^n)$
- Generalized Bernoulli's inequality
- Problem evaluating $ \int_{0}^{\pi/2}\frac{x}{\tan x}dx $
- So close yet so far Finding $\int \frac {\sec x \tan x}{3x+5} dx$
- How to properly apply the Lie Series
- Counting Rows of a Truth Table that Satisfy a Condition
- Asymptotic expansion of an integral
- How to interpret “computable real numbers are not countable, and are complete”?
- How to compute localizations of quotients of polynomial rings