School of Mathematics Colloquium

Existence of Cannon-Thurston map

by Dr Swathi Krishna (TIFR, Mumbai)

Asia/Kolkata
AG-69

AG-69

Description
Abstract: Let $G$ be a hyperbolic group and $H$ be a hyperbolic subgroup of $G$. If the embedding $H\to G$ extends continuously to a map between the Gromov compactifications of the groups, this extension is called a Cannon-Thurston map (CT). While it is known that not every hyperbolic subgroup embedding in a hyperbolic group admits CT, over time the existence of CT has been proven in many cases. We will start with a survey of these results and move on to the following case where CT exists. Let $1\to N \to G \stackrel{\pi}{\to} Q\to 1$ be a short exact sequence of non-elementary hyperbolic groups and $K=\pi^{-1}(Q_1)$, where $Q_1$ is a qi-embedded subgroup of $Q$. Then $K$ is hyperbolic and $K\to G$ admits CT. This is part of joint work with Pranab Sardar.
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