The reachability semantics for Petri nets can be studied using open Petri nets. For us, an
“open” Petri net is one with certain places designated as inputs and outputs via a cospan of …

This is a case study in the design of computer programs based upon the twin themes of
abstraction and constructivity. We consider the unification of terms--a symbol-manipulative …

One goal of applied category theory is to better understand networks appearing throughout
science and engineering. Here we introduce" structured cospans" as a way to study …

Functional programs are merely equations; they may be manipulated by straightforward
equational reasoning. In particular, one can use this style of reasoning to calculate …

We introduce E-unification, weak E-unification, E-upper bound, E-lower bound, and E-
generalization problems, and the corresponding notions of unification, weak unification …

There are two quite distinct ways to talk about type theory as it occurs in theoretical computer
science; namely, logical type theory versus algebraic type theory. Many computer languages …

We now introduce one of the triumphs of category theory--a descriptive framework of great
generality occurring widely in mathematics and programming. As the reader will be aware …

The theory of sketches is discussed briefly and the example of natural numbers is treated in
détail both in a simple and a more complicated version-Then the functor Setof (-) is …

The presentation is based on a correspondence of typed functional programming with
category theory. Apart from this, it is a blend of that from standard textbooks such as [Mac …

This paper outlines STePS (Structured Technique for Program Specification), a systematic
method for designing programs. The procedures (supported by established system design …