This is just a request for clarification, an attempt to penetrate the notation. Is this what you have in mind? If so: (1) the operation is not definite, any point $P_{k+1,j}$ on the circle arc between $P_{k,j}$ and $P_{k,j+1}$ forms a right angle; and (2) the subsequent polygons could be nonconvex. But perhaps I am misinterpreting... <br /> ![ngon right angles][1] [1]: https://i.sstatic.net/Wzynb.jpg