92,340 reputation
581169
bio website von-eitzen.de/math/tntrep.xml
location Bonn, Germany
age 48
visits member for 1 year, 7 months
seen 8 hours ago

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


8h
comment Example of dependent but conditional independent
$P(Y)=P(Z)=\frac12$, but $P(Y,Z)=\frac12\cdot \frac34\cdot\frac34+\frac12\cdot\frac14\cdot\frac14=\frac5{16}\ne\frac14$.
8h
answered Lower bound of the index of a subgroup of a non abelian simple group
8h
comment Lower bound of the index of a subgroup of a non abelian simple group
You mean proper subgroup.
8h
revised Need to negate this proposition!
added 38 characters in body
8h
answered Need to negate this proposition!
9h
comment Need to negate this proposition!
The "and" between quantors better viewed as a "such that".
9h
comment A and B are sets. Prove that A=B iff P(A) = P(B) where P is the power set.
Just note that $\bigcup P(A)=A$.
9h
answered Example of dependent but conditional independent
9h
answered What is “the orbit of a permutation”? Is the term “orbit” consistent with that for group action?
9h
comment How to get a number that is divisible by $n$ - without obviously seeing it?
@user2345215 D'oh, if you want to read a recipe that enforces divisibility, your mind simply ignores such crucial words. :) - Jsut like sentnces with lots of msipselld words are stlil more or less raedable ...
10h
comment sub-algebra of continuous real valued functions without unit must vanish at a point
Don't we need proper subalgebra?
10h
comment How to get a number that is divisible by $n$ - without obviously seeing it?
Well, let's see. Think of a three-digit number, but not ending in zero or five and digit sum not a multiple of three. Now take it to the eighth power and subtract one. I magically foresee that the result is divisible by fifteen. - Your audience won't like you.
12h
answered Least Squares Approximation for odd functions question
13h
comment Solve an Angle-Side-Angle special case triangle if it has an obtuse angle?
Why dont you try the law of sines? It works.
13h
revised Compact sets of real number
added 9 characters in body
13h
comment Compact sets of real number
Can you use that a continuous function on a compact set attains its minimum? Or that the product of compact spaces is compact?
13h
answered Why does the result follow?
13h
comment Insights in solving systems of eqn?
The for the moment forget about $I_3AI_4$, whatever that is. Try to obtain new - simpler - equations by adding / subtracting known equations. For example, add the first and third to immediately see what $x_3$ must be ...
16h
answered If $xy=x^{-1}y^{-1}$, does this imply $x=x^{-1}$
16h
comment In how many ways can i build this String : abbcccdddd?
As it seems, there is only one way :)