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100 views

Possible shifts in finite elementary cellular automata

I investigated the long term behaviour of a pair of black cells ■■ on a circle of $N$ cells under the action of each of Wolfram's rules $R$. For each combination $(R,N)$ I determined the first ...
Hans-Peter Stricker's user avatar
6 votes
3 answers
681 views

When is $2\varphi(n) > n$ – and how to prove it?

When coloring the squares of the Ulam spiral not only by black and white (for being prime or non-prime) but by shades of grey representing the normalized totient function $\varphi(n)/n$ and ...
Hans-Peter Stricker's user avatar
5 votes
1 answer
503 views

Explaining patterns in modular multiplication graphs

Let the multiplication graph $n/m$ be the graph with $m$ points distributed evenly on a circle and a line between two points $a$, $b$ when $an \equiv b\operatorname{mod} m$. These graphs often look ...
Hans-Peter Stricker's user avatar
1 vote
1 answer
378 views

Why is $n_{n^2-1}$ the smallest graph that clearly shows the structure of multiplication by $n$?

Initially, I wanted to ask this question as a puzzle. Consider a regular $m$-gon. Let $0$ be the lower corner and count the corners clockwise. Let $n_m$ be the multiplication-by-$n$-graph of $...
Hans-Peter Stricker's user avatar
12 votes
2 answers
1k views

How to visualize finiteness of class number?

As the question title asks for, how do others "visualize" the finiteness of class number with algebro-geometric insight? I just think of it as a result in algebraic number theory and not one in ...
Squid with Black Bean Sauce's user avatar
3 votes
0 answers
238 views

Visualization of hidden structures in numbers

[Please allow me a note: The way desribed below allows to depict functions $f:X^2 \rightarrow Y$ completely in two dimensions (without hiding or omitting any information). This allows for depicting ...
Hans-Peter Stricker's user avatar
36 votes
2 answers
3k views

How to visualize Dirichlet’s unit theorem?

As the question title asks for, how do others "visualize" Dirichlet’s unit theorem? I just think of it as a result in algebraic number theory and not one in algebraic geometry. Bonus points for ...
Squid with Black Bean Sauce's user avatar
14 votes
1 answer
2k views

How to visualize the Frobenius endomorphism?

As the question title asks for, how do others "visualize" the Frobenius endomorphism? I asked some people in real life and they said they didn't know and that I could go and ask on MO and possibly get ...
Squid with Black Bean Sauce's user avatar