Accessible parts of the boundary for domains in metric measure spaces

We prove in the setting of \(Q\)-Ahlfors regular PI-spaces following result: if a domain has uniformly large boundary when measured with respect to \(s\)-dimensional Hausdorff content, then its visible \(t\)-dimensional content for every \(0<t<s\leq Q-1\). The is set points that can be reached by John curve from fixed point \(z_{0}\in \Omega\). This generalizes recent results Koskela-Nandi-Nicolau (from \(\mathbb R^2\)) and Azzam (\(\mathbb R^n\)). In particular, our approach shows phenomenon independent linear structure space.