10 research outputs found
Session Types in Abelian Logic
There was a PhD student who says "I found a pair of wooden shoes. I put a
coin in the left and a key in the right. Next morning, I found those objects in
the opposite shoes." We do not claim existence of such shoes, but propose a
similar programming abstraction in the context of typed lambda calculi. The
result, which we call the Amida calculus, extends Abramsky's linear lambda
calculus LF and characterizes Abelian logic.Comment: In Proceedings PLACES 2013, arXiv:1312.221
A type checking algorithm for qualified session types
We present a type checking algorithm for establishing a session-based
discipline in the pi calculus of Milner, Parrow and Walker. Our session types
are qualified as linear or unrestricted. Linearly typed communication channels
are guaranteed to occur in exactly one thread, possibly multiple times;
afterwards they evolve as unrestricted channels. Session protocols are
described by a type constructor that denotes the two ends of one and the same
communication channel. We ensure the soundness of the algorithm by showing that
processes consuming all linear resources are accepted by a type system
preserving typings during the computation and that type checking is consistent
w.r.t. structural congruence.Comment: In Proceedings WWV 2011, arXiv:1108.208
Cut Reduction in Linear Logic as Asynchronous Session-Typed Communication
Prior work has shown that intuitionistic linear logic can be seen as a
session-type discipline for the pi-calculus, where cut reduction in
the sequent calculus corresponds to synchronous process reduction. In
this paper, we exhibit a new process assignment from the asynchronous,
polyadic pi-calculus to exactly the same proof rules. Proof-theoretically, the difference between these interpretations can
be understood through permutations of inference rules that preserve
observational equivalence of closed processes in the synchronous case.
We also show that, under this new asynchronous interpretation, cut
reductions correspond to a natural asynchronous buffered session
semantics, where each session is allocated a separate communication
buffer
Typing Copyless Message Passing
We present a calculus that models a form of process interaction based on
copyless message passing, in the style of Singularity OS. The calculus is
equipped with a type system ensuring that well-typed processes are free from
memory faults, memory leaks, and communication errors. The type system is
essentially linear, but we show that linearity alone is inadequate, because it
leaves room for scenarios where well-typed processes leak significant amounts
of memory. We address these problems basing the type system upon an original
variant of session types.Comment: 50 page
On Projecting Processes into Session Types
We define session types as projections of the behaviour of processes with respect to the operations processes perform on channels. This calls for a parallel composition operator over session types denoting the simultaneous access to a channel by two or more processes. The proposed approach allows us to define a semantically grounded theory of session types that does not require the linear usage of channels. However, type preservation and progress can only be guaranteed for processes that never receive channels they already own. A number of examples show that the resulting framework validates existing session-type theories and unifies them to some extent.</jats:p
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
A linear account of session types in the pi calculus
Abstract. We present a reconstruction of session types in a conventional pi calculus where types are qualified as linear or unrestricted. Linearly typed communication channels are guaranteed to occur in exactly one thread, possibly multiple times. We equip types with a constructor that denotes the two ends of a same communication channel. In order to assess the flexibility of the new type system, we provide three distinct encodings (from the linear lambda calculus, from the linear pi calculus, and from the pi calculus with polarized variables) into our system. For each language we present operational and typing correspondences, showing that our system effectively subsumes the linear pi calculus as well as foregoing works on session types