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arXiv · 2403.05735

The Flapping Birds in the Pentagram Zoo

Richard Evan Schwartz
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Abstract

We study the $(k+1,k)$ diagonal map for $k=2,3,4,...$. We call this map $\Delta_k$. The map $\Delta_1$ is the pentagram map and $\Delta_k$ is a generalization. $\Delta_k$ does not preserve convexity, but we prove that $\Delta_k$ preserves a subset $B_k$ of certain star-shaped polygons which we call $k$-birds. The action of $\Delta_k$ on $B_k$ seems similar to the action of $\Delta_1$ on the space of convex polygons. We show that some classic geometric results about $\Delta_1$ generalize to this setting.

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Richard Evan Schwartz. 2024-03-09. The Flapping Birds in the Pentagram Zoo. https://arxiv.org/abs/2403.05735

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