128,148 reputation
9121250
bio website von-eitzen.de/math/tntrep.xml
location Bonn, Germany
age 49
visits member for 2 years, 5 months
seen 22 hours ago

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


Feb
15
comment How many different elements can we obtain by multiplying all element in a group?
With $G=S_n$, $n>3$ we have $S\subseteq A_n$ because the products must be even permutations (there is an even number of odd perumtations in $S_n$).
Feb
15
comment How many different elements can we obtain by multiplying all element in a group?
@DavidPeterson aka. $|G|$ is odd
Feb
15
comment How many different elements can we obtain by multiplying all element in a group?
With $G=S_3$ the answer is $S_3\setminus A_3$, i.e. the set of 2-cycles, $S=\{(1\,2),(1\,3),(2\,3)\}$. One inclusion is clear as the product is always an odd permutation. The other follows by symmetry.
Feb
15
comment How many different elements can we obtain by multiplying all element in a group?
@5xum Not necessarily $S=\{1\}$, only $|S|=1$. Check with $G=\mathbb Z/2\mathbb Z$.
Feb
15
comment Why isn't the inductive set _the_ set of natural numbers?
@drhab With your $x$, $y:=\mathbb N$ is $\in x$ but $y\cup \{y\}$ is not. You do need a limit ordinal (or at least add something that starts at some $S\notin \mathbb N$)
Feb
15
answered Why isn't the inductive set _the_ set of natural numbers?
Feb
15
revised Can any piecewise function be represented as a traditional equation?
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Feb
15
answered Can any piecewise function be represented as a traditional equation?
Feb
15
comment Can any piecewise function be represented as a traditional equation?
@kennycoc Your unit step is continuous in its domain of definition. And what does "Anything that is not a piecewise function" mean? Do you accept limits, for example?
Feb
15
comment Can any piecewise function be represented as a traditional equation?
@MichaelC.Grant With your second question you miss the OP's point, I guess. The expression $(x+|x|)/2$ is fine for hime in contrast to anything using \begin{cases}..\end{cases}
Feb
15
comment Can any piecewise function be represented as a traditional equation?
What is to be accepted as traditional? Whatever you accept, I assume all your traditional functions are continuous (in their domain of definition), which makes the composition of non-continuous functions impossible.
Feb
15
comment pseudorandom numbers generation technique and mathematical induction
Second question: The "advantage" of those multiple choice test is that you don't have to be 100% sure about correctness. For $n=0$ the sum evaluates to $2$. Which of the candidates evaluates to $2$ for $n=0$?
Feb
15
revised Set builder notation
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Feb
15
answered Set builder notation
Feb
15
answered Number of solutions for (a-x)(b-y)-1=0
Feb
15
answered Nontrivial Homomorphism(s) from $\mathbb{Z_3}$ to $S_3$ - Fraleigh p. 134 13.37
Feb
15
reviewed Leave Open What's the maximum deviation from loan amortization
Feb
15
answered Closest point out of collision
Feb
15
answered A closed form for the recursion?
Feb
15
revised Show that finitely many disjoint discs can be inscribed in a unit square with total area approaching 1
added 1649 characters in body