Coinductive Field of Exact Real Numbers and General Corecursion
Institute for Computing and Information Sciences, Faculty of Science; Radboud University Nijmegen
Toernooiveld 1, 6525 ED, Nijmegen, The Netherlands
In this article we present a method to define algebraic structure (field operations) on a representation of real numbers by coinductive streams. The field operations will be given in two algorithms (homographic and quadratic algorithm) that operate on streams of Möbius maps. The algorithms can be seen as coalgebra maps on the coalgebra of streams and hence they will be formalised as general corecursive functions. We use the machinery of Coq proof assistant for coinductive types to present the formalisation.