Dehn twist
= Dehn twist
{c}
{wiki}
A Dehn twist $T_\gamma$ cuts an oriented surface along a simple closed curve $\gamma$, rotates one side once, and glues it back. If a curve or arc $\alpha$ has nonzero geometric intersection with $\gamma$, the iterates $T_\gamma^n(\alpha)$ usually represent distinct isotopy classes, with intersection numbers growing linearly in $|n|$.