Formal language

About: Formal language is a research topic. Over the lifetime, 5763 publications have been published within this topic receiving 154114 citations.

A storeless model of aliasing and its abstractions using finite representations of right-regular equivalence relations

Abstract: The problem of interference and aliasing in programming languages with structured, dynamically allocated data is studied The author starts from a novel semantic model of data aliasing, then elaborates new results in formal language theory in order to represent its invariants, and finally uses these results to derive an efficient and online algorithm for statically determining dynamic aliasing properties of structured data >

Automatic Hardware Synthesis from Specifications: A Case Study

Abstract: We propose to use a formal specification language as a high-level hardware description language. Formal languages allow for compact, unambiguous representations and yield designs that are correct by construction. The idea of automatic synthesis from specifications is old, but used to be completely impractical. Recently, great strides towards efficient synthesis from specifications have been made. In this paper we extend these recent methods to generate compact circuits and we show their practicality by synthesizing an arbiter for ARM's AMBA AHB bus and a generalized buffer from specifications given in PSL. These are the first industrial examples that have been synthesized automatically from their specifications

Managing Knowledge in a World of Networks

Abstract: The main problem encountered when starting verification of goals for some formal system, is the ambiguity of those goals when they are specified in natural language. To verify goals given in natural language, a translation of those goals to the formalism of the verification tool is required. The main concern is to assure equivalence of the final translation and the original. A structured method is required to assure equivalence in every case. This article proposes a goal formalisation method in five steps, in which the domain expert is involved in such a way that the correctness of the result can be assured. The contribution of this article is a conceptual goal model, a formal expression language for this model, and a structured method which transforms any input goal to a fully formalised goal in the required target formalism. The proposed formalisation method guarantees essential properties like correctness, traceability, reduced variability and reusability.

High-level small-step operational semantics for transactions

Abstract: Software transactions have received significant attention as a way to simplify shared-memory concurrent programming, but insufficient focus has been given to the precise meaning of software transactions or their interaction with other language features. This work begins to rectify that situation by presenting a family of formal languages that model a wide variety of behaviors for software transactions. These languages abstract away implementation details of transactional memory, providing high-level definitions suitable for programming languages. We use small-step semantics in order to represent explicitly the interleaved execution of threads that is necessary to investigate pertinent issues.We demonstrate the value of our core approach to modeling transactions by investigating two issues in depth. First, we consider parallel nesting, in which parallelism and transactions can nest arbitrarily. Second, we present multiple models for weak isolation, in which nontransactional code can violate the isolation of a transaction. For both, type-and-effect systems let us soundly and statically restrict what computation can occur inside or outside a transaction. We prove some key language-equivalence theorems to confirm that under sufficient static restrictions, in particular that each mutable memory location is used outside transactions or inside transactions (but not both), no program can determine whether the language implementation uses weak isolation or strong isolation.

Formal language theory: refining the Chomsky hierarchy

Abstract: The first part of this article gives a brief overview of the four levels of the Chomsky hierarchy, with a special emphasis on context-free and regular languages. It then recapitulates the arguments why neither regular nor context-free grammar is sufficiently expressive to capture all phenomena in the natural language syntax. In the second part, two refinements of the Chomsky hierarchy are reviewed, which are both relevant to the extant research in cognitive science: the mildly context-sensitive languages (which are located between context-free and context-sensitive languages), and the sub-regular hierarchy (which distinguishes several levels of complexity within the class of regular languages).