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2d
comment What is the mathematical difference between group and category?
Why the category of groups and one object small groupids are not isomorphic?
2d
comment What is the center of power series?
In my reading, the center is at $x=-4$.
May
25
comment Find sum of Solutions in a hard Equation
What the hack are you doing?
May
24
revised Quadratic residue and permutation
added 123 characters in body
May
24
answered Quadratic residue and permutation
May
24
comment Etingof problem 2.15.1 Representations of sl(2)
Why is $v'$ an eigenvector? You wrote $H(v')=(-1)^{k+1}\lambda^kv$ and not $v'$ on the right hand side.
May
24
comment What's the most general geometry branch?
Logic. State as axioms the basic properties you want, and take a language of 'curves', 'lines' (perhaps 'vectors') with a central predicate 'to be tangent'.
May
24
comment Derivative of a Rational function $f(x)=\sqrt{2x-5\over3x+1}$
Use one more property of the exponentials and apply Leibniz' rule for differentiating a product.
May
23
comment Compute $\lim_{n \to \infty} \left(\frac{1}{\sqrt{n^3+1}} + \frac{1}{\sqrt{n^3+4}} + \cdots + \frac{1}{\sqrt{n^3+n^2}}\right)$
Rather $\frac n{\sqrt{n^3+1}}$.
May
23
comment $G$ a group and $H$,$K$ subgroups, $kHk^{-1} \subseteq H \implies kHk^{-1} = H$?
You mean $H$ is finite, don't you?
May
23
comment $G$ a group and $H$,$K$ subgroups, $kHk^{-1} \subseteq H \implies kHk^{-1} = H$?
$K$ has no real role here, we can take arbitrary $k$ and set $K$ the cyclic $K:=\langle k\rangle$, for example.
May
23
comment Heyting algebras and infinite distributive law
Can you write an answer then for your own question?
May
21
comment There is exactly one pair of homeomorphic spaces
Well, yes, you are right. However, it is just a hint that works in this situation to get a conjecture which two might be homeomorphic.
May
20
answered Prove Operator is a Projector
May
20
answered Equivalency of the set of real numbers to the set of all continuous real functions?
May
20
answered There is exactly one pair of homeomorphic spaces
May
19
comment linear independency in equation of linear span
$\{v_1\}$ is linearly independent $\iff\ v_1\ne 0$, and it doesn't contradict that $\{v_1,w_2\}$ is linearly independent.
May
18
answered Endomorphic Function Definition
May
18
answered Boolean Algebra expanding using absorption
May
12
comment Do combinatorial species have adjoints?
Since $\mathbb B$ is a grupoid, both the unit and the counit of any adjunction are invertible, hence any adjunction is an (adjoint) equivalence.