Hartog's extension theorem for codimension 2
I need to use a version of Hartog's extension theorem, that I did not find by googling around. However I think I found a solution myself, and wanted ...
Apr 11, 2026 1 VIEWS
Topic: General
5104 Articles 
Good examples of Everyday Isomorphisms
Whilst trying to explain the concept of an isomorphism to a non-mathematician, it didn't seem to suffice to me to just give a precise definition, or ...
Apr 11, 2026 1 VIEWS
Taylor series of $\csc(x)$
How can I compute the Taylor series of $\csc(x):=\frac{1}{\sin(x)}$ at $0$? When I google this I can see that indeed this series can be computed, the firs...
Apr 11, 2026 1 VIEWS
Stochastic calculus book recommendation
I'm a quantitative researcher at a financial company. I have a PhD in math, but I'm an algebraist, so I only took the two required analysis cour...
Apr 11, 2026 2 VIEWS
What's actually the definition of the product of morphisms?
I have heard different versions of it, in wikipedia, it says that: The unique morphism f is called the product of morphisms f1 and f2 and is denoted < ...
Apr 11, 2026 1 VIEWS
Upper Bound vs. Least Upper Bound
I am reading Rudin's Principles of Mathematical Analysis in order to prepare for my first course in Real Analysis I intend to take this fall. The boo...
Apr 11, 2026 1 VIEWS
Trying to understand the meaning of symmetry
The picture below is the solution to the following problem as presented in my book: Find the area of the region that lies inside both curves $$r = 8 + \co...
Apr 11, 2026 1 VIEWS
Every kernel is monic
Before I begin: I'm new to category theory. I'm trying to show that if $k$ is a kernel of some morphism of some category, then it is monic. Here...
Apr 11, 2026 1 VIEWS
How to find lines of invariant points?
Every time I try a question on this topic I get it wrong. My textbook says: Invariant points satisfy $B\begin{pmatrix}u\\ v\end{pmatrix}=\begin{pmatrix}u\...
Apr 11, 2026 2 VIEWS
Formal name of vector identity
I just derived this simple vector identity $$\mathbf{a}\cdot\left(\mathbf{b}\times\left(\mathbf{b} \times\mathbf{c}\right)\right) = \left(\mathbf{a}\times...
Apr 11, 2026 1 VIEWS
Real and imaginary parts of a complex function [closed]
Is it always possible to separate the real and the imaginary parts of a complex function ? And why ? I always did it by calculations, but is there a theor...
Apr 11, 2026 1 VIEWS
If a triangle has two angles congruent, then two sides are congruent
If a triangle has two angles congruent, then two sides are congruent. How can this be proven without using ASA. I have been trying to solve this but I kee...
Apr 11, 2026 1 VIEWS