Time:  12:00  13:20 
Room: 
Doherty Hall 1117 (PLEASE NOTE THE NONSTANDARD PLACE!)

Speaker: 
Lars Birkedal
IT University of Copenhagen 
Title: 
Solutions of Generalized Recursive MetricSpace Equations

Abstract: 
It is well known that one can use an adaptation of the inverselimit construction to solve recursive equations in the category of complete ultrametric spaces. We show that this construction generalizes to a large class of categories with metricspace structure on each set of morphisms: the exact nature of the objects is less important. In particular, the construction immediately applies to categories where the objects are ultrametric spaces with 'extra structure', and where the morphisms preserve this extra structure. The generalization is inspired by classical domaintheoretic work by Smyth and Plotkin. Our primary motivation for solving generalized recursive metricspace equations comes from recent and ongoing work on Kripkestyle models of programming languages with higherorder store in which the sets of worlds must be recursively defined. We show a series of examples motivated by this line of work. Joint work with Kristian Stovring and Jacob Thamsborg 