Special IMM groups

Abstract

Italiano-Martelli-Migliorini recently constructed hyperbolic groups which have non-hyperbolic subgroups of finite type. Using a closely related construction, Llosa Isenrich-Martelli-Py constructed hyperbolic groups with subgroups of type $F_3$ but not $F_4$. We observe that these hyperbolic groups can be chosen to be special in the sense of Haglund-Wise.

8 pages. Final version, to appear in Bull. Lond. Math. Soc