Automatic Verification of Erlang-Style Concurrency

This paper presents an approach to verify safety properties of Erlang-style, higher-order concurrent programs automatically. Inspired by Core Erlang, we introduce Lambda-Actor, a prototypical functional language with pattern-matching algebraic data types, augmented with process creation and asynchronous message-passing primitives. We formalise an abstract model of Lambda-Actor programs called Actor Communicating System (ACS) which has a natural interpretation as a vector addition system, for which some verification problems are decidable. We give a parametric abstract interpretation framework for Lambda-Actor and use it to build a polytime computable, flow-based, abstract semantics of Lambda-Actor programs, which we then use to bootstrap the ACS construction, thus deriving a more accurate abstract model of the input program. We have constructed Soter, a tool implementation of the verification method, thereby obtaining the first fully-automatic, infinite-state model checker for a core fragment of Erlang. We find that in practice our abstraction technique is accurate enough to verify an interesting range of safety properties. Though the ACS coverability problem is Expspace-complete, Soter can analyse these verification problems surprisingly efficiently.Comment: 12 pages plus appendix, 4 figures, 1 table. The tool is available at http://mjolnir.cs.ox.ac.uk/soter

Compile-Time Analysis and Specialization of Clocks in Concurrent Programs

Clocks are a mechanism for providing synchronization barriers in concurrent programming languages. They are usually implemented using primitive communication mechanisms and thus spare the programmer from reasoning about low-level implementation details such as remote procedure calls and error conditions. Clocks provide flexibility, but programs often use them in specific ways that do not require their full implementation. In this paper, we describe a tool that mitigates the overhead of general-purpose clocks by statically analyzing how programs use them and choosing optimized implementations when available. We tackle the clock implementation in the standard library of the X10 programming language—a parallel, distributed object-oriented language. We report our findings for a small set of analyses and benchmarks. Our tool only adds a few seconds to analysis time, making it practical to use as part of a compilation chain

Integrating interactive tools using concurrent haskell and synchronous events

In this paper we describe how existing interactive tools can be integrated using Concurrent Haskell and synchronous events. The base technology is a higher-order approach to concurrency as in CML extended with a framework for handling external events of the environment. These events are represented as first class synchronous events to achieve a uniform, composable approach to event handling. Adaptors are interposed between the external event sources and the internal set of listening agents to achieve this degree of abstraction. A substantially improved integration framework compared to existing technology (such as for example the combination of Tcl/Tk with expect) is then provided. With this basis it is for example possible to wrap a GUI around the hugs interpreter with very little work required.Eje: Conferencia latinoamericana de programación funcionalRed de Universidades con Carreras en Informática (RedUNCI

A Mechanized Theory of Communication Analysis in CML

For this master\u27s thesis, I have developed a formal semantics of a language with concurrent processes (or threads), an initial formal analysis, along with related theorems and formal proofs. The language under analysis is a very simplified version of Concurrent ML. The formal analysis recasts an analysis with informal proofs developed by Reppy and Xiao. It categorizes communication described by programs into simple topologies. One description of topologies is static; that is, it describes all static topologies of a program in a finite number of steps. Another description is dynamic; that is, it describes topologies in terms of running a program for an arbitrary number of steps. The main formal theorem states that the static analysis is sound with respect to the dynamic analysis. Two versions of the static analysis have been developed so far; one with lower precision, and one with higher precision. The higher precision analysis is closer to the work by Reppy and Xiao, but contains many more details making it more challenging to prove formally than the lower precision analysis. The proofs for the soundness theorems of the lower precision analysis have been mechanically verified using Isabelle/HOL, while the higher precision analysis is currently under development. Indeed, one of the motivations for implementing the analysis in a mechanical setting is to enable gradual extension of analysis and language without introducing uncaught bugs in the definitions or proofs. The definitions used in this formal theory differ significantly from that of Reppy and Xiao, in order to aid formal reasoning. Thus, recasting Reppy and Xiao\u27s work was far more nuanced than a straightforward syntactic transliteration. Although the definitions are structurally quite different, their philosophical equivalence is hopefully apparent. In this formal theory, the dynamic semantics of Concurrent ML consists of a CEK machine. The static semantics consists of a control flow analysis (0CFA), defined in terms of constraints

Scalability of multi-agent systems : proposal for a dissertation

This work proposes a generic approach for achieving scalability of multi-agent-systems (MAS). The key to reach that goal is to introduce a self-organization mechanism allowing systems to configure themselves to any application scale and nature. The work outlines such a mechanism, which can be introduced to any multi-agent system. Focus is put on two systems, InteRRaP and MECCA, and on two applications, the transportation domain, realized using InteRRaP agents, and a traffic telematics application modelled with MECCA agents. All systems and applications are briefly characterized in this work and relations to other fields of research are pointed out

Practical and effective higher-order optimizations

Inlining is an optimization that replaces a call to a function with that function’s body. This optimization not only reduces the overhead of a function call, but can expose additional optimization oppor-tunities to the compiler, such as removing redundant operations or unused conditional branches. Another optimization, copy propaga-tion, replaces a redundant copy of a still-live variable with the origi-nal. Copy propagation can reduce the total number of live variables, reducing register pressure and memory usage, and possibly elimi-nating redundant memory-to-memory copies. In practice, both of these optimizations are implemented in nearly every modern com-piler. These two optimizations are practical to implement and effec-tive in first-order languages, but in languages with lexically-scoped first-class functions (aka, closures), these optimizations are no

Cryptography and Its Applications in Information Security

Nowadays, mankind is living in a cyber world. Modern technologies involve fast communication links between potentially billions of devices through complex networks (satellite, mobile phone, Internet, Internet of Things (IoT), etc.). The main concern posed by these entangled complex networks is their protection against passive and active attacks that could compromise public security (sabotage, espionage, cyber-terrorism) and privacy. This Special Issue “Cryptography and Its Applications in Information Security” addresses the range of problems related to the security of information in networks and multimedia communications and to bring together researchers, practitioners, and industrials interested by such questions. It consists of eight peer-reviewed papers, however easily understandable, that cover a range of subjects and applications related security of information