The Algebra of Directed Acyclic Graphs

We give an algebraic presentation of directed acyclic graph structure, introducing a symmetric monoidal equational theory whose free PROP we characterise as that of finite abstract dags with input/output interfaces. Our development provides an initial-algebra semantics for dag structure

Classical Logic with Mendler Induction

We investigate (co-)induction in Classical Logic under the propositions-as-types paradigm, considering propositional, second-order, and (co-)inductive types. Specifically, we introduce an extension of the Dual Calculus with a Mendler-style (co-)iterator that remains strongly normalizing under head reduction. We prove this using a non-constructive realizability argument.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/978-3-319-27683-0_

Classical logic with Mendler induction

We investigate (co-) induction in classical logic under the propositions-as-types paradigm, considering propositional, second-order and (co-) inductive types. Specifically, we introduce an extension of the Dual Calculus with a Mendler-style (co-) iterator and show that it is strongly normalizing. We prove this using a reducibility argument

Implementation of an orchestration language as a haskell domain specific language

Even though concurrent programming has been a hot topic of discussion in Computer Science for the past 30 years, the community has yet to settle on a, or a few standard approaches to implement concurrent programs. But as more and more cores inhabit our CPUs and more and more services are made available on the web the problem of coordinating different tasks becomes increasingly relevant. The present paper addresses this problem with an implementation of the orchestration language Orc as a domain specific language in Haskell. Orc was, therefore, realized as a combinator library using the lightweight threads and the communication and synchronization primitives of the Concurrent Haskell library. With this implementation it becomes possible to create orchestrations that re-use existing Haskell code and, conversely, re-use orchestrations inside other Haskell programs. The complexity inherent to distributed computation, entails the need for the classification of efficient, re-usable, concurrent programming patterns. The paper discusses how the calculus of recursive schemes used in the derivation of functional programs, scales up to a distributed setting. It is shown, in particular, how to parallelize the entire class of binary tree hylomorphisms.FCT -Fuel Cell Technologies Program(PTDC/EIA/73252/2006