123,719 reputation
8117240
bio website von-eitzen.de/math/tntrep.xml
location Bonn, Germany
age 49
visits member for 2 years, 3 months
seen 5 hours ago

I did study math and had a knack for it, but I am sooo out of that business now ...


Dec
15
revised Showing $\gamma < \sqrt{1/3}$ without a computer
deleted 1 character in body; edited title
Dec
15
reviewed Close PDF of Gamma R.V.
Dec
15
reviewed Close Marriage theorem. Proof.
Dec
15
answered Proofs involving positive real numbers
Dec
15
answered Proving that a function is absolutely monotonic on a given interval
Dec
15
comment Theorem with seemingly reduntant part
Oh, maybe I now see what you mean: Maybe You confuse $u{.}u\ge 0\quad \land \quad(u{.}u=0\Leftrightarrow u=0)$ with $(u{.}u\ge 0\land u{.}u=0)\iff u=0$.
Dec
15
answered Theorem with seemingly reduntant part
Dec
15
answered Problem of axiomatic euclidean geometry
Dec
15
answered Why $P_1\neq P_1P_2$?
Dec
15
revised A possible defining characteristic of primitive roots.
added 18 characters in body
Dec
15
comment A possible defining characteristic of primitive roots.
Viewing $t$ as residue $\bmod p$ makes little sense as the exponent should rather be considered $\bmod {p-1}$.
Dec
15
answered A possible defining characteristic of primitive roots.
Dec
15
comment How to find solutions of coin weighing problems with multiple light coins and prove optimality
The special case $k=N$ of your second problem is well-known: As the weights can be arbitrary, it makes no sense to ever put more than one coin into each pan of the balance. Then the problem reduces to sort with the minimal number of comparisons. You should find something in Knuth, The Art of Computer Programming, Sorting and Searching.
Dec
15
comment How to find solutions of coin weighing problems with multiple light coins and prove optimality
The straightforward informationtheoretical bound is not always obtainable. For example ${50\choose 3}=19600<3^9$, but the best "first move" is to compare $12:12$ coins; then the balance shows "equal" in $6344$ and "left" (and "right") in $6628$ cases; since $6628>3^8$, more than $9$ rounds may be needed.
Dec
15
accepted Construct quadrangle with given angles and perpendicular diagonals
Dec
15
comment Construct quadrangle with given angles and perpendicular diagonals
I'll accept this as it clearly demonstrates constructability and it seems that an explicit construction (at least one straightforwardly derived from these expressions) is a task for long winter nights ;)
Dec
15
revised Suppose $P(X \in B) \in \{0,1\}$ for all $B \in \mathcal B(\mathbb R)$. Show $X = c$, $P$-almost-surely.
added 251 characters in body
Dec
15
answered Suppose $P(X \in B) \in \{0,1\}$ for all $B \in \mathcal B(\mathbb R)$. Show $X = c$, $P$-almost-surely.
Dec
15
revised Order of $\mathrm{GL}_n(\mathbb F_p)$ for $p$ prime
edited body
Dec
15
answered Order of $\mathrm{GL}_n(\mathbb F_p)$ for $p$ prime