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I'm curious to all things new to me.

Thanks for your help!


13h
comment Graph theory: Why people use “K” to represent complete graph?
Thanks! Kazimierz Kuratowski was born in 1896. I cannot believe this fundamental concept was defined later than 1896.
13h
comment Graph theory: Why people use “K” to represent complete graph?
@Martin That's an possible explanation. In my opinion, they are fundamental concepts in graph theory hence it is not that easy to tell which one comes first.
13h
comment Graph theory: Why people use “K” to represent complete graph?
@martini I know nothing about German and google translation tells me that which possibly be wrong.
13h
asked Graph theory: Why people use “K” to represent complete graph?
Jan
10
asked What's the relationship between interior/exterior/boundary point and limit point?
Jan
10
comment Real Analysis: Is $\emptyset$ a open set in $X$?
If G is empty you can not choose a x that satisfies this. So G is not open.
Jan
10
asked Real Analysis: Is $\emptyset$ a open set in $X$?
Jan
9
revised What is the difference between open ball and neighborhood in real analysis?
added 365 characters in body
Jan
9
asked What is the difference between open ball and neighborhood in real analysis?
Dec
31
accepted How to geometrically interpret $\sum^{p}_{1}\lambda_{i}(A)=\operatorname{tr}(A)$?
Dec
23
revised How to geometrically interpret $\sum^{p}_{1}\lambda_{i}(A)=\operatorname{tr}(A)$?
added 170 characters in body
Dec
22
revised How to geometrically interpret $\sum^{p}_{1}\lambda_{i}(A)=\operatorname{tr}(A)$?
added 121 characters in body
Dec
22
asked How to geometrically interpret $\sum^{p}_{1}\lambda_{i}(A)=\operatorname{tr}(A)$?
Dec
9
awarded  Enthusiast
Dec
6
accepted How to understand spectral decomposition geometrically
Nov
29
asked How to understand spectral decomposition geometrically
Nov
27
accepted How to prove in a graph $G$, its incidence matrix $A$ is totally unimodular if and only if $G$ is a bipartite graph?
Nov
27
accepted Why $\sigma_{\bar{x}}=\frac{\sigma}{\sqrt{n}}$
Nov
27
accepted What is degree of freedom in statistics?
Nov
27
accepted What's the relationship between Cauchy-Schwarz Inequality and Extended Cauchy-Schwarz Inequality?