Hagen von Eitzen
Reputation
97/100 score
 May 8 comment The number of subsets of cardinality less than $\kappa$ of a cardinal $\kappa$ is $\kappa$ If $\kappa =\aleph_1$ then certainly $\#S\ge 2^{\aleph_0}$, which may be $>\kappa$. May 8 comment Is there a special name for matrices $A^T A$ and $A A^T$? How is "symmetric positive semi-dfinite" too general? Could you exhibit a symmetric positive semidefinite matrix that is not of this form? May 8 revised Is there a special name for matrices $A^T A$ and $A A^T$? edited tags May 8 answered Supremum of a sequence of functions May 8 comment Dust coating a length of road that is 1.25 miles long. @RossMillikan For me as European that is precisely the hard part of it ... May 8 answered Prove $(s_n)$ converges, where $s_{n+1} \lt r(s_n)$. May 8 comment Finding value of the summation @user2399614 There is no need to reconsider May 8 reviewed Leave Closed Is $\phi$ convex if it is continuous and $\phi \Big(\frac{x+y}{2}\Big)\le \frac{1}{2}\phi (x) +\frac{1}{2} \phi (y)$ May 8 answered Is $\exp$ the only function satisfying $f(x)=\displaystyle \int_{-x}^{+\infty} f(-t) dt$? May 8 answered Finding value of the summation May 8 answered Interesting Power Series May 8 answered How many poker hands have exactly one pair? May 8 comment Mathematical structures with name reffering to a country Catalan numbers ar not really an example because the name is derived from Eugène Charles Catalan May 8 answered Prove that $ln(x)$ is concave by using the following definition for $ln(x)$ May 8 answered Accurate Formula and One Old-Exam Questions?! May 7 answered How is it possible to have a function that is both bounded an entire? May 7 comment Find some value of $n$ such that $|a_n - a| < 10^{-1000}$ You should rather find that $a_n\to 0$. May 7 reviewed Looks OK How is this true? Bookworm puzzle May 7 reviewed Looks OK Integration of $(\tan x\sec x)^3$ May 7 answered limits and continuity: irrational and rational piecewise function