What Are Polymorphically-Typed Ambients?

Abstract: The Ambient Calculus was developed by Cardelli and Gordon as a formal framework to study issues of mobility and migrant code. We consider an Ambient Calculus where ambients transport and exchange programs rather that just inert data. We propose different senses in which such a calculus can be said to be polymorphically typed, and design accordingly a polymorphic type system for it. Our type system assigns types to embedded programs and what we call behaviors to processes; a denotational semantics of behaviors is then proposed, here called trace semantics, underlying much of the remaining analysis. We state and prove a Subject Reduction property for our polymorphically typed calculus. Based on techniques borrowed from finite automata theory, type-checking of fully type-annotated processes is shown to be decidable; the time complexity of our decision procedure is exponential (this is a worst-case in theory, arguably not encountered in practice). Our polymorphically-typed calculus is a conservative extension of the typed Ambient Calculus originally proposed by Cardelli and Gordon

TyCO + Linear channels

We present an extension to the TyCO type system that is able to identify linear channels. We prove some technical results (e.g. type preservation w.r.t. reduction) and present an algorithm for inferring channels usage from process expressions. Our major contribution is the inference of linear information in a calculus with recursive equations rather than replicatio

A Lexically Scoped Distributed π\pi-Calculus

We define the syntax, the operational semantics, and a type system for lsd-pi, an asynchronous and distributed $\pi$-calculus with local communication and process migration. The calculus follows a simple model of distribution for mobile calculi, with a lexical scoping mechanism that provides both for remote communication and for process migration, making explicit migration primitives superfluou

Tipski sistemi za kontrolu memorije i prava pristupa

Three issues will be elaborated and disussed in the proposed thesis. The first is administration and control of data access rights in networks with XML data, with emphasis on data security. The second is the administration and control of access rights to data in computer networks with RDF data, with emphasis on data privacy. The third is prevention of errors and memory leaks, as well as communication errors, generated by programs written in Sing # language in the presence of exceptions. For all three issues, there will be presented formal models with corresponding type systems and showed the absence of undesired behavior i.e. errors in networks or programs.У тези су разматрана три проблема. Први је администрација и контрола права приступа података у рачунарској мрежи са XML подацима, са нагласком на безбедости посматраних података. Други је администрација и котрола права приступа подацима у рачунарској мрежи са RDF подацима, са нагласком на приватности посматраних података. Трећи је превенција грешака и цурења меморије, као и грешака у комуникацији генерисаним програмима написаних на језику Sing# у којима су присутни изузеци. За сва три проблема биће предложени формални модели и одговарајући типски системи помоћу којих се показује одсуство неповољних понашања тј. грешака у мрежама односно програмима.U tezi su razmatrana tri problema. Prvi je administracija i kontrola prava pristupa podataka u računarskoj mreži sa XML podacima, sa naglaskom na bezbedosti posmatranih podataka. Drugi je administracija i kotrola prava pristupa podacima u računarskoj mreži sa RDF podacima, sa naglaskom na privatnosti posmatranih podataka. Treći je prevencija grešaka i curenja memorije, kao i grešaka u komunikaciji generisanim programima napisanih na jeziku Sing# u kojima su prisutni izuzeci. Za sva tri problema biće predloženi formalni modeli i odgovarajući tipski sistemi pomoću kojih se pokazuje odsustvo nepovoljnih ponašanja tj. grešaka u mrežama odnosno programima