High energy semiclassical wave functions in rational multi-connected and other (Sinai-like) billiards determined by their periodic orbits

The methods of the high energy semiclassical quantization in the rational polygon billiards used in our earlier papers are generalized to an arbitrary rational multi-connected polygon billiards i.e. to the billiards which is a rational polygon with other rational polygons inside them "rotated" with respect to the "mother" ones by rational angles. The respective procedure is described fully and its most important aspects are discussed. This generalization allows us to apply the method to arbitrary billiards with curved boundaries and with multi-connected areas where the respective semiclassical quantization is determined by the shortest periodic orbits of the billiards. As an example of the latter case the Sinai-like billiards is considered which is the right angle triangle with one of its acute angles equal to π/6 and with the circular hole in it.