Distributed Logic Objects: A Fragment of Rewriting Logic and its Implementation

Abstract This paper presents a logic language (called Distributed Logic Objects, DLO for short) that supports objects, messages and inheritance. The operational semantics of the language is given in terms of rewriting rules acting upon the (possibly distributed) state of the system. In this sense, the logic underlying the language is Rewriting Logic. In the paper we discuss the implementation of this language on distributed memory MIMD architectures, and we describe the advantages achieved in terms of flexibility, scalability and load balancing. In more detail, the implementation is obtained by translating logic objects into a concurrent logic language based on multi-head clauses, taking advantage from its distributed implementation on a massively parallel architecture. In the underlying implementation, objects are clusters of processes, objects' state is represented by logical variables, message-passing communication between objects is performed via multi-head clauses, and inheritance is mapped into clause union. Some interesting features such as transparent object migration and intensional messages are easily achieved thanks to the underlying support. In the paper, we also sketch a (direct) distributed implementation supporting the indexing of clauses for single-named methods

The Parma Polyhedra Library: Toward a Complete Set of Numerical Abstractions for the Analysis and Verification of Hardware and Software Systems

Since its inception as a student project in 2001, initially just for the handling (as the name implies) of convex polyhedra, the Parma Polyhedra Library has been continuously improved and extended by joining scrupulous research on the theoretical foundations of (possibly non-convex) numerical abstractions to a total adherence to the best available practices in software development. Even though it is still not fully mature and functionally complete, the Parma Polyhedra Library already offers a combination of functionality, reliability, usability and performance that is not matched by similar, freely available libraries. In this paper, we present the main features of the current version of the library, emphasizing those that distinguish it from other similar libraries and those that are important for applications in the field of analysis and verification of hardware and software systems.Comment: 38 pages, 2 figures, 3 listings, 3 table

A Microscopic Simulation Laboratory for Evaluation of Off-street Parking Systems

The parking industry produces an enormous amount of data every day that, properly analyzed, will change the way the industry operates. The collected data form patterns that, in most cases, would allow parking operators and property owners to better understand how to maximize revenue and decrease operating expenses and support the decisions such as how to set specific parking policies (e.g. electrical charging only parking space) to achieve the sustainable and eco-friendly parking. However, there lacks an intelligent tool to assess the layout design and operational performance of parking lots to reduce the externalities and increase the revenue. To address this issue, this research presents a comprehensive agent-based framework for microscopic off-street parking system simulation. A rule-based parking simulation logic programming model is formulated. The proposed simulation model can effectively capture the behaviors of drivers and pedestrians as well as spatial and temporal interactions of traffic dynamics in the parking system. A methodology for data collection, processing, and extraction of user behaviors in the parking system is also developed. A Long-Short Term Memory (LSTM) neural network is used to predict the arrival and departure of the vehicles. The proposed simulator is implemented in Java and a Software as a Service (SaaS) graphic user interface is designed to analyze and visualize the simulation results. This study finds the active capacity of the parking system, which is defined as the largest number of actively moving vehicles in the parking system under the facility layout. In the system application of the real world testbed, the numerical tests show (a) the smart check-in device has marginal benefits in vehicle waiting time; (b) the flexible pricing policy may increase the average daily revenue if the elasticity of the price is not involved; (c) the number of electrical charging only spots has a negative impact on the performance of the parking facility; and (d) the rear-in only policy may increase the duration of parking maneuvers and reduce the efficiency during the arrival rush hour. Application of the developed simulation system using a real-world case demonstrates its capability of providing informative quantitative measures to support decisions in designing, maintaining, and operating smart parking facilities

Scheduling Irregular Workloads on GPUs

This doctoral research aims at understanding the nature of the overhead for data irregular GPU workloads, proposing a solution, and examining the consequences of the result. We propose a novel, retry-free GPU workload scheduler for irregular workloads. When used in a Breadth First Search (BFS) algorithm, the proposed simple, monolithic concurrent queue scales to within 10% of ideal scalability on AMD’s Fiji GPU with 14,336 active threads. The dissertation presents an important finding that the retry overhead associated with Compare and Swap (CAS) operations is the principle reason why concurrent queues do not scale well as the number of clients increases in a massively multi-threaded environment

Tools and Models for High Level Parallel and Grid Programming

When algorithmic skeletons were first introduced by Cole in late 1980 the idea had an almost immediate success. The skeletal approach has been proved to be effective when application algorithms can be expressed in terms of skeletons composition. However, despite both their effectiveness and the progress made in skeletal systems design and implementation, algorithmic skeletons remain absent from mainstream practice. Cole and other researchers, focused the problem. They recognized the issues affecting skeletal systems and stated a set of principles that have to be tackled in order to make them more effective and to take skeletal programming into the parallel mainstream. In this thesis we propose tools and models for addressing some among the skeletal programming environments issues. We describe three novel approaches aimed at enhancing skeletons based systems from different angles. First, we present a model we conceived that allows algorithmic skeletons customization exploiting the macro data-flow abstraction. Then we present two results about the exploitation of meta-programming techniques for the run-time generation and optimization of macro data-flow graphs. In particular, we show how to generate and how to optimize macro data-flow graphs accordingly both to programmers provided non-functional requirements and to execution platform features. The last result we present are the Behavioural Skeletons, an approach aimed at addressing the limitations of skeletal programming environments when used for the development of component-based Grid applications. We validated all the approaches conducting several test, performed exploiting a set of tools we developed.Comment: PhD Thesis, 2008, IMT Institute for Advanced Studies, Lucca. arXiv admin note: text overlap with arXiv:1002.2722 by other author

The design and implementation of a multiparadigm programming language.

by Chi-keung Luk.Thesis (M.Phil.)--Chinese University of Hong Kong, 1993.Includes bibliographical references (leaves 169-174).Preface --- p.xiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Programming Languages --- p.2Chapter 1.2 --- Programming Paradigms --- p.2Chapter 1.2.1 --- What is a programming paradigm --- p.2Chapter 1.2.2 --- Which came first? Languages or paradigms? --- p.2Chapter 1.2.3 --- Overview of some paradigms --- p.4Chapter 1.2.4 --- A spectrum of paradigms --- p.6Chapter 1.2.5 --- Mulitparadigm systems --- p.7Chapter 1.3 --- The Objectives of this research --- p.8Chapter 2 --- "Studies of the object-oriented, the logic and the functional paradigms" --- p.10Chapter 2.1 --- The Object-Oriented Paradigm --- p.10Chapter 2.1.1 --- Basic components --- p.10Chapter 2.1.2 --- Motivations --- p.11Chapter 2.1.3 --- Some related issues --- p.12Chapter 2.1.4 --- Computational models for object-oriented programming --- p.16Chapter 2.2 --- The Functional Paradigm --- p.18Chapter 2.2.1 --- Basic concepts --- p.18Chapter 2.2.2 --- Lambda calculus --- p.20Chapter 2.2.3 --- The characteristics of functional programs --- p.21Chapter 2.2.4 --- Practicality of functional programming --- p.25Chapter 2.3 --- The Logic Paradigm --- p.28Chapter 2.3.1 --- Relations --- p.28Chapter 2.3.2 --- Logic programs --- p.29Chapter 2.3.3 --- The opportunity for parallelism --- p.30Chapter 2.4 --- Summary --- p.31Chapter 3 --- A survey of some existing multiparadigm languages --- p.32Chapter 3.1 --- Logic + Object-Oriented --- p.33Chapter 3.1.1 --- LogiC++ --- p.33Chapter 3.1.2 --- Intermission --- p.34Chapter 3.1.3 --- Object-Oriented Programming in Prolog (OOPP) --- p.36Chapter 3.1.4 --- Communication Prolog Unit (CPU) --- p.37Chapter 3.1.5 --- DLP --- p.37Chapter 3.1.6 --- Representing Objects in a Logic Programming Language with Scoping Constructs (OLPSC) --- p.39Chapter 3.1.7 --- KSL/Logic --- p.40Chapter 3.1.8 --- Orient84/K --- p.41Chapter 3.1.9 --- Vulcan --- p.42Chapter 3.1.10 --- The Bridge approach --- p.43Chapter 3.1.11 --- Discussion --- p.44Chapter 3.2 --- Functional + Object-Oriented --- p.46Chapter 3.2.1 --- PROOF --- p.46Chapter 3.2.2 --- A Functional Language with Classes (FLC) --- p.47Chapter 3.2.3 --- Common Lisp Object System (CLOS) --- p.49Chapter 3.2.4 --- FOOPS --- p.50Chapter 3.2.5 --- Discussion --- p.51Chapter 3.3 --- Logic + Functional --- p.52Chapter 3.3.1 --- HOPE --- p.52Chapter 3.3.2 --- FUNLOG --- p.54Chapter 3.3.3 --- F* --- p.55Chapter 3.3.4 --- LEAF --- p.56Chapter 3.3.5 --- Applog --- p.57Chapter 3.3.6 --- Discussion --- p.58Chapter 3.4 --- Logic + Functional + Object-Oriented --- p.61Chapter 3.4.1 --- Paradise --- p.61Chapter 3.4.2 --- LIFE --- p.62Chapter 3.4.3 --- UNIFORM --- p.63Chapter 3.4.4 --- G --- p.64Chapter 3.4.5 --- FOOPlog --- p.66Chapter 3.4.6 --- Logic and Objects (L&O) --- p.66Chapter 3.4.7 --- Discussion --- p.67Chapter 4 --- The design of a multiparadigm language I --- p.70Chapter 4.1 --- An Object-Oriented Framework --- p.71Chapter 4.1.1 --- A hierarchy of classes --- p.71Chapter 4.1.2 --- Program structure --- p.71Chapter 4.1.3 --- Parametric classes --- p.72Chapter 4.1.4 --- Inheritance --- p.73Chapter 4.1.5 --- The meanings of classes and methods --- p.75Chapter 4.1.6 --- Objects and messages --- p.75Chapter 4.2 --- The logic Subclasses --- p.76Chapter 4.2.1 --- Syntax --- p.76Chapter 4.2.2 --- Distributed inference --- p.76Chapter 4.2.3 --- Adding functions and expressions to logic programs --- p.77Chapter 4.2.4 --- State modelling --- p.79Chapter 4.3 --- The functional Subclasses --- p.80Chapter 4.3.1 --- The syntax of functions --- p.80Chapter 4.3.2 --- Abstract data types --- p.81Chapter 4.3.3 --- Augmented list comprehensions --- p.82Chapter 4.4 --- The Semantic Foundation of I Programs --- p.84Chapter 4.4.1 --- T1* : Transform functions into Horn clauses --- p.84Chapter 4.4.2 --- T2*: Transform object-oriented features into pure logic --- p.85Chapter 4.5 --- Exploiting Parallelism in I Programs --- p.89Chapter 4.5.1 --- Inter-object parallelism --- p.89Chapter 4.5.2 --- Intra-object parallelism --- p.92Chapter 4.6 --- Discussion --- p.96Chapter 5 --- An implementation of a prototype of I --- p.99Chapter 5.1 --- System Overview --- p.99Chapter 5.2 --- I-to-Prolog Translation --- p.101Chapter 5.2.1 --- Pass 1 - lexical and syntax analysis --- p.101Chapter 5.2.2 --- Pass 2 - Class Table Construction and Semantic Checking --- p.101Chapter 5.2.3 --- Pass 3 - Determination of Multiple Inheritance Precedence --- p.105Chapter 5.2.4 --- Pass 4 - Translation of the directive part --- p.110Chapter 5.2.5 --- Pass 5 - Creation of Prolog source code for an I object --- p.110Chapter 5.2.6 --- Using expressions in logic methods --- p.112Chapter 5.3 --- I-to-LML Translation --- p.114Chapter 5.4 --- The Run-time Handler --- p.117Chapter 5.4.1 --- Object Management --- p.118Chapter 5.4.2 --- Process Management and Message Passing --- p.121Chapter 6 --- Some applications written in I --- p.125Chapter 6.1 --- Modeling of a State Space Search --- p.125Chapter 6.2 --- A Solution to the N-queen Problem --- p.129Chapter 6.3 --- Object-Oriented Modeling of a Database --- p.131Chapter 6.4 --- A Simple Expert System --- p.133Chapter 6.5 --- Summary --- p.138Chapter 7 --- Conclusion and future work --- p.139Chapter 7.1 --- Conclusion --- p.139Chapter 7.2 --- Future Work --- p.141Chapter A --- Language manual --- p.146Chapter A.1 --- Introduction --- p.146Chapter A.2 --- Syntax --- p.146Chapter A.2.1 --- The lexical specification --- p.146Chapter A.2.2 --- The syntax specification --- p.149Chapter A3 --- Classes --- p.152Chapter A.4 --- Object Creation and Method Invocation --- p.153Chapter A.5 --- The logic Subclasses --- p.155Chapter A.6 --- The functional Subclasses --- p.156Chapter A.7 --- Types --- p.158Chapter A.8 --- Mutable States --- p.158Chapter B --- User's guide --- p.160Chapter B.1 --- System Calls --- p.160Chapter B.2 --- Configuration Parameters --- p.162Chapter B.3 --- Errors --- p.163Chapter B.4 --- Implementation Limits --- p.164Chapter B.5 --- How to install the system --- p.164Chapter B.6 --- How to use the system --- p.164Chapter B.7 --- How to recompile the system --- p.166Chapter B.8 --- Directory arrangement --- p.167Chapter C --- List of publications --- p.168Bibliography --- p.16

Flashix: modular verification of a concurrent and crash-safe flash file system

The Flashix project has developed the first realistic verified file system for Flash memory. This paper gives an overview over the project and the theory used. Specification is based on modular components and subcomponents, which may have concurrent implementations connected via refinement. Functional correctness and crash-safety of each component is verified separately. We highlight some components that were recently added to improve efficiency, such as file caches and concurrent garbage collection. The project generates 18K of C code that runs under Linux. We evaluate how efficiency has improved and compare to UBIFS, the most recent flash file system implementation available for the Linux kernel

Self-organization and autonomy in computational networks: agents-based contractual workflow paradigm

We describe an agents-based contractual workflow paradigm for Self-organization and autonomy in computational networks. The agent-based paradigm can be interpreted as the outcome arising out of deterministic, nondeterministic or stochastic interaction among a set of agents that includes the environment. These interactions are like chemical reactions and result in self-organization. Since the reaction rules are inherently parallel, any number of actions can be performed cooperatively or competitively among the subsets of elements, so that the agents carry out the required actions. Also we describe the application of this paradigm in finding short duration paths, chemical- patent mining, and in cloud computing services