Compositions of Belyi Maps and their Extended Monodromy Groups

Abstract

Given a composition of Bely\u{\i} maps $\beta \circ \gamma: X \rightarrow Z$, paths between edges of $\beta$ are extended to form loops, then lifted by $\gamma$. These liftings are then studied to understand how loops in $Z$ act on edges of $\beta \circ \gamma$, demonstrating the group operation in $\mathop{\mathrm{Mon}} \beta \circ \gamma \unlhd \mathop{\mathrm{Mon}} \gamma \wr \mathop{\mathrm{Mon}} \beta$. Abstracting away the specific Bely\u{\i} map $\gamma$ and finding the image of $\pi_{1}(Z)$ in $\pi_{1}(Y) \wr \mathop{\mathrm{Mon}} \beta$ instead allows subsequently determining $\mathop{\mathrm{Mon}} \beta \circ \gamma$, for any $\gamma$, using only the monodromy representation of $\gamma$.