5,191 research outputs found
An Algebra of Synchronous Scheduling Interfaces
In this paper we propose an algebra of synchronous scheduling interfaces
which combines the expressiveness of Boolean algebra for logical and functional
behaviour with the min-max-plus arithmetic for quantifying the non-functional
aspects of synchronous interfaces. The interface theory arises from a
realisability interpretation of intuitionistic modal logic (also known as
Curry-Howard-Isomorphism or propositions-as-types principle). The resulting
algebra of interface types aims to provide a general setting for specifying
type-directed and compositional analyses of worst-case scheduling bounds. It
covers synchronous control flow under concurrent, multi-processing or
multi-threading execution and permits precise statements about exactness and
coverage of the analyses supporting a variety of abstractions. The paper
illustrates the expressiveness of the algebra by way of some examples taken
from network flow problems, shortest-path, task scheduling and worst-case
reaction times in synchronous programming.Comment: In Proceedings FIT 2010, arXiv:1101.426
A Formal, Resource Consumption-Preserving Translation of Actors to Haskell
We present a formal translation of an actor-based language with cooperative
scheduling to the functional language Haskell. The translation is proven
correct with respect to a formal semantics of the source language and a
high-level operational semantics of the target, i.e. a subset of Haskell. The
main correctness theorem is expressed in terms of a simulation relation between
the operational semantics of actor programs and their translation. This allows
us to then prove that the resource consumption is preserved over this
translation, as we establish an equivalence of the cost of the original and
Haskell-translated execution traces.Comment: Pre-proceedings paper presented at the 26th International Symposium
on Logic-Based Program Synthesis and Transformation (LOPSTR 2016), Edinburgh,
Scotland UK, 6-8 September 2016 (arXiv:1608.02534
Scheduling with processing set restrictions : a survey
2008-2009 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
An overview of the ciao multiparadigm language and program development environment and its design philosophy
We describe some of the novel aspects and motivations behind
the design and implementation of the Ciao multiparadigm programming system. An important aspect of Ciao is that it provides the programmer with a large number of useful features from different programming paradigms and styles, and that the use of each of these features can be turned on and off at will for each program module. Thus, a given module may be using e.g. higher order functions and constraints, while another module may be using objects, predicates, and concurrency. Furthermore, the language is designed to be extensible in a simple and modular way. Another important aspect of Ciao is its programming environment, which provides a powerful preprocessor (with an associated assertion language) capable of statically finding non-trivial bugs, verifying that programs comply with specifications, and performing many types of program optimizations. Such optimizations produce code that is highly competitive with other dynamic languages or, when the highest levéis of optimization are used, even that of static languages, all while retaining the interactive development environment of a dynamic language. The environment also includes a powerful auto-documenter. The paper provides an informal overview of the language and program development environment. It aims at illustrating the design philosophy rather than at being exhaustive, which would be impossible in the format of a paper, pointing instead to the existing literature on the system
Reachability Analysis of Communicating Pushdown Systems
The reachability analysis of recursive programs that communicate
asynchronously over reliable FIFO channels calls for restrictions to ensure
decidability. Our first result characterizes communication topologies with a
decidable reachability problem restricted to eager runs (i.e., runs where
messages are either received immediately after being sent, or never received).
The problem is EXPTIME-complete in the decidable case. The second result is a
doubly exponential time algorithm for bounded context analysis in this setting,
together with a matching lower bound. Both results extend and improve previous
work from La Torre et al
Type systems for distributed programs: session communication
Distributed systems are everywhere around us and guaranteeing their correctness is of paramount importance. It is natural to expect that these systems interact and communicate among them to achieve a common task.
In this work, we develop techniques based on types and type systems for the verification of correctness, consistency and safety properties related to communication in complex distributed systems. We study advanced safety properties related to communication, like deadlock or lock freedom and progress. We study session types in the pi-calculus describing distributed systems and communication-centric computation. Most importantly, we de- fine an encoding of the session pi-calculus into the standard typed pi-calculus in order to understand the expressive power of these concurrent calculi. We show how to derive in the session pi-calculus basic properties, like type safety or complex ones, like progress, by exploiting this encoding
Resource Control for Synchronous Cooperative Threads
We develop new methods to statically bound the resources needed for the
execution of systems of concurrent, interactive threads. Our study is concerned
with a \emph{synchronous} model of interaction based on cooperative threads
whose execution proceeds in synchronous rounds called instants. Our
contribution is a system of compositional static analyses to guarantee that
each instant terminates and to bound the size of the values computed by the
system as a function of the size of its parameters at the beginning of the
instant. Our method generalises an approach designed for first-order functional
languages that relies on a combination of standard termination techniques for
term rewriting systems and an analysis of the size of the computed values based
on the notion of quasi-interpretation. We show that these two methods can be
combined to obtain an explicit polynomial bound on the resources needed for the
execution of the system during an instant. As a second contribution, we
introduce a virtual machine and a related bytecode thus producing a precise
description of the resources needed for the execution of a system. In this
context, we present a suitable control flow analysis that allows to formulte
the static analyses for resource control at byte code level
Numerical Integration and Dynamic Discretization in Heuristic Search Planning over Hybrid Domains
In this paper we look into the problem of planning over hybrid domains, where
change can be both discrete and instantaneous, or continuous over time. In
addition, it is required that each state on the trajectory induced by the
execution of plans complies with a given set of global constraints. We approach
the computation of plans for such domains as the problem of searching over a
deterministic state model. In this model, some of the successor states are
obtained by solving numerically the so-called initial value problem over a set
of ordinary differential equations (ODE) given by the current plan prefix.
These equations hold over time intervals whose duration is determined
dynamically, according to whether zero crossing events take place for a set of
invariant conditions. The resulting planner, FS+, incorporates these features
together with effective heuristic guidance. FS+ does not impose any of the
syntactic restrictions on process effects often found on the existing
literature on Hybrid Planning. A key concept of our approach is that a clear
separation is struck between planning and simulation time steps. The former is
the time allowed to observe the evolution of a given dynamical system before
committing to a future course of action, whilst the later is part of the model
of the environment. FS+ is shown to be a robust planner over a diverse set of
hybrid domains, taken from the existing literature on hybrid planning and
systems.Comment: 17 page
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