# Partition of Non-Regular Prime Stellated Cyclic Polygons into Rotation Classes

## Contents

## Theorem

Let $p$ be an odd prime.

Let $C$ be a circle whose center is $O$.

Consider the set $P$ of $p$ points on the circumference of $C$ dividing it into $p$ equal arcs.

Let $S$ be the set of all non-regular stellated $p$-gons whose vertices are the elements of $P$.

Let $\sim$ denote the equivalence relation on $S$ defined as:

- $\forall \tuple {a, b} \in S \times S: a \sim b \iff$ there exists a plane rotation about $O$ transforming $a$ to $b$.

Then the $\sim$-equivalence classes of $S$ into which $S$ can thereby be partitioned all have cardinality $p$.

## Proof

## Examples

### Pentagons

The equivalence classes by rotation of the non-regular stellated pentagons whose vertices are equally spaced on the circumference of a circle are depicted thus.

Thus there are $2$ equivalence classes, each with $5$ elements.

Matt Westwood suggests that these equivalence classes could be nicknamed **fish** and **bat**.

## Sources

- 1971: George E. Andrews:
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