1. It probed links among asymptotic invariants of covering towers, algebraic invariants of residually finite groups and dynamical properties and invariants of profinite actions.

2. Bauxites are residually enriched rocks, mostly composed of Al-hydroxides (gibbsite, boehmite and diaspore), kaolinite, Fe-oxy-hydroxides and Ti-oxides, which form from intense lateritic weathering of aluminosilicate protoliths