A Complete, Co-Inductive Syntactic Theory of Sequential Control and State

We present a new co-inductive syntactic theory, eager normal form bisimilarity, for the untyped call-by-value lambda calculus extended with continuations and mutable references. We demonstrate that the associated bisimulation proof principle is easy to use and that it is a powerful tool for proving equivalences between recursive imperative higher-order programs. The theory is modular in the sense that eager normal form bisimilarity for each of the calculi extended with continuations and/or mutable references is a fully abstract extension of eager normal form bisimilarity for its sub-calculi. For each calculus, we prove that eager normal form bisimilarity is a congruence and is sound with respect to contextual equivalence. Furthermore, for the calculus with both continuations and mutable references, we show that eager normal form bisimilarity is complete: it coincides with contextual equivalence

Language acquisition and machine learning

In this paper, we review recent progress in the field of machine learning and examine its implications for computational models of language acquisition. As a framework for understanding this research, we propose four component tasks involved in learning from experience - aggregation, clustering, characterization, and storage. We then consider four common problems studied by machine learning researchers - learning from examples, heuristics learning, conceptual clustering, and learning macro-operators - describing each in terms of our framework. After this, we turn to the problem of grammar acquisition, relating this problem to other learning tasks and reviewing four AI systems that have addressed the problem. Finally, we note some limitations of the earlier work and propose an alternative approach to modeling the mechanisms underlying language acquisition

Fifty years of Hoare's Logic

We present a history of Hoare's logic.Comment: 79 pages. To appear in Formal Aspects of Computin

Putting Operational Techniques to the Test: A Syntactic Theory for Behavioral Verilog

AbstractWe present a syntactic theory for the behavioral subset of the Verilog Hardware Description Language. Due to the complexity of the language, the construction of this theory represents a serious test of the suitability of syntactic operational techniques for reasoning about industrial languages. Overall, we have found that these techniques are rather robust but with a few caveats. Our theory formalizes the simulation cycle explicitly, exposes a number of ambiguities and inconsistencies in the language reference manual (LRM), and is the most accurate known description of this subset of Verilog, with respect to the LRM. The syntactic theory has been used to automatically derive a simulator for Verilog

A formal semantics for control and data flow in the gannet service-based system-on-chip architecture

There is a growing demand for solutions which allow the design of large and complex reconfigurable Systems-on- Chip (SoC) at high abstraction levels. The Gannet project proposes a functional programming approach for high-abstraction design of very large SoCs. Gannet is a distributed service-based SoC architecture, i.e. a network of services offered by hardware or software cores. The Gannet SoC is task-level reconfigurable: it performs tasks by executing functional task description programs using a demand-driven dataflow mechanism. The Gannet architecture combines the flexible connectivity offered by a Networkon- Chip with the functional language paradigm to create a fully concurrent distributed SoC with the option to completely separate data flows from control flows. This feature is essential to avoid a bottleneck at he controller for run-time control of multiple high-throughput data flows. In this paper we present the Gannet architecture and language and introduce an operational semantics to formally describe the mechanism to separate control and data flows

Maude: specification and programming in rewriting logic

Maude is a high-level language and a high-performance system supporting executable specification and declarative programming in rewriting logic. Since rewriting logic contains equational logic, Maude also supports equational specification and programming in its sublanguage of functional modules and theories. The underlying equational logic chosen for Maude is membership equational logic, that has sorts, subsorts, operator overloading, and partiality definable by membership and equality conditions. Rewriting logic is reflective, in the sense of being able to express its own metalevel at the object level. Reflection is systematically exploited in Maude endowing the language with powerful metaprogramming capabilities, including both user-definable module operations and declarative strategies to guide the deduction process. This paper explains and illustrates with examples the main concepts of Maude's language design, including its underlying logic, functional, system and object-oriented modules, as well as parameterized modules, theories, and views. We also explain how Maude supports reflection, metaprogramming and internal strategies. The paper outlines the principles underlying the Maude system implementation, including its semicompilation techniques. We conclude with some remarks about applications, work on a formal environment for Maude, and a mobile language extension of Maude

Synchronous Online Philosophy Courses: An Experiment in Progress

There are two main ways to teach a course online: synchronously or asynchronously. In an asynchronous course, students can log on at their convenience and do the course work. In a synchronous course, there is a requirement that all students be online at specific times, to allow for a shared course environment. In this article, the author discusses the strengths and weaknesses of synchronous online learning for the teaching of undergraduate philosophy courses. The author discusses specific strategies and technologies he uses in the teaching of online philosophy courses. In particular, the author discusses how he uses videoconferencing to create a classroom-like environment in an online class

Engineering a static verification tool for GPU kernels

We report on practical experiences over the last 2.5 years related to the engineering of GPUVerify, a static verification tool for OpenCL and CUDA GPU kernels, plotting the progress of GPUVerify from a prototype to a fully functional and relatively efficient analysis tool. Our hope is that this experience report will serve the verification community by helping to inform future tooling efforts. © 2014 Springer International Publishing