Dehn functions and the space of marked groups

Abstract

In the space of marked group, we suppose that a sequence $(G_i,X_i)$ converges to $(G,X)$, where $G$ is finitely presented. We obtain an inequality which connects Dehn functions of $G_i$s and $G$. As a result, we show that if a sequence $(K,X_i)$ converges to a hyperbolic marked group, then $K$ is already hyperbolic.

5 pages, Corollary 1 in the previous version was not true