“…On the other extreme, at the high energy limit, for compact billiard tables, mechanical HIS limit to the billiard flow in the specified billiard table. The theory for intermediate energy values includes local analysis near periodic orbits [5] and near smooth convex boundaries [22,2], and, for some specific classes of HIS, hyperbolic behavior [19], Liuoville integrable [11,6,3,16,14] and near-integrable [15] dynamics were established. A class of quasi-integrable HIS, which is related to the quasi-integrable dynamics in families of polygonal right angled corners, was introduced in [1].…”