  The algebraic mapping torus $M_{\Phi}$ of a group $G$ with an automorphism
$\Phi$ is the HNN-extension of $G$ in which conjugation by the stable letter
performs $\Phi$. We classify the Dehn functions of $M_{\Phi}$ in terms of
$\Phi$ for a number of right-angled Artin groups $G$, including all
$3$-generator right-angled Artin groups and $F_k \times F_l$ for all $k,l \geq
2$.

Group Theory