Hagen von Eitzen
Reputation
393/400 score
 54m revised what does $\langle u,v\rangle$ mean? Beautified 1h answered Infinite averages 4h comment What is an Empty set? Just as there is a differne between putting a bag (and its content) into another bag or putting the contents of the first bag into the second. (Car Mummert's shopping bag analogy is just to good) 4h revised semicontinious functions in topology space added 76 characters in body 4h comment Check if convex polygon is completely contained completely within another convex polygon. @JPtheK9 A convex polygon is the intersection of finitely many half planes. A point is inside the polygon iff it is inside all these half planes. 10h comment he first isomorphism theorem to deduce that G/K ⇠= H. In other words: What is the only thing mentioned inthe problem statement taht is a homomorphism? What is its image? What is its kernel? 10h answered $a^n-n^a \mid b^n-n^b$ for all large $n$ 11h comment Power Series Problem. @RohitDuggal There's no reason to believe that the limit exists. 11h comment Power Series Problem. Does Lt mean $\limsup$? 11h revised Power Series Problem. added 11 characters in body 12h answered Sum of elements of a finite field is zero 12h answered Check if convex polygon is completely contained completely within another convex polygon. 13h comment What is an irreducible polynomial in $\mathbb{Z}$ that has root $\sqrt{2}+\sqrt{3}$? An alternative way to show irreducibilirty: We know all four roots of the polynomial: $\pm\sqrt 2\pm\sqrt 3$ None of them is rational, hence no linear factor. The sum of $\sqrt2+\sqrt 3$ and another root is rational only for $-\sqrt 2-\sqrt 3$, but then the product is irrational, hence no two of the roots can be the roots of a quedratic factor 21h answered Show that $S$ is a field 21h answered On a question about finite metric spaces 22h answered What is an irreducible polynomial in $\mathbb{Z}$ that has root $\sqrt{2}+\sqrt{3}$? 22h answered Eight inches of heavy, wet snow are equivalent to four inches of rain. Estimate the water content in 17 inches of heavy, wet snow. 22h answered How to find the largest disk in a square when there are points we must avoid? 22h comment Limits of square root function Is the second thing the limit of the negative square root? Or th elimit as we approach $3$ from below? 22h comment Characterisation of continuous functions whose support is compact Then again, what kind of classification would be suitable? You might exhibit specific such functions, say with $f_n(x)=0$ for $|x|\ge n$ (and $f_n(x)\ne0$ othrwise). Then any continuous function with compact support is of the form $f(x)=f_n(x)g(x)$ with continous $g$ for some $n$ ...