Dear friends, I am a PhD Student in Computer Science at Departamento de Informatica, UFPE, Brazil, and I need to study the theory of sheaves and its conexion with logic. However I am finding some dificulties concerning matterials who have an intuitive explanation of the subject. I am reading Michael Fourman and D. Scott's Sheaves and Logic paper. It would be helpful if you could give me an intuition about the following questions: Is there any intuition about the notions of global and local objects? What is the connection between global and local objects, and, for example, partial and total functions? Is there any intuition about the existence predicate E:|A|->\omega? What is a singleton? In the paper "Identity and Existence", in the same proceedings, Scott formalized the notion of partial objects (e.g.partial functions). If we are modelling the standard intuitionistic logic, the local objects makes sense? Let me explain what I want to get. Is sheaves an adequate model for intuitionistic logic just when we want to formalize the notion of partial objects? And if we are working with standard intuitionistic logic, does the category of structure generated by a first order theory contain strutures with, for example, partial functions? Is there any intuitive written material about the subject? My best regards Regivan --------------------------- Regivan H. N. Santiago http://www.di.ufpe.br/~rhns Recife-Pernambuco/Brazil ---------------------------