Formal language

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

ASN.1 Communication Between Heterogeneous Systems

Abstract: I Introduction and History of the Notation 1 Prologue 2 Utilitarian Introduction to ASN.1 3 ASN.1 and the OSI Reference Model 4 Your First Steps with ASN.1 5 Basics of ASN.1 6 History 7 Protocols Specified in ASN.1 II User's Guide and Reference Manual 8 Introduction to the Reference Manual 9 Modules and Assignments 10 Basic Types 11 Character String Types 12 Constructed Types, Tagging, Extensibility Rules 13 Subtype Constraints 14 Presentation Context Switching Types 15 Information Object Classes, Objects, and Object Sets 16 Enough To Read Macros 17 Parameterization III Encoding Rules and Transfer Syntaxes 18 Basic Encoding Rules (BER) 19 Canonical and Distinguished Encoding Rules (CER and DER) 20 Packed Encoding Rules (PER) 21 Other Encoding Rules IV ASN.1 Applications 22 Tools 23 ASN.1 and the Formal Languages SDL, TTCN, GDMO 24 Other Abstract Syntax Notations 25 Epilogue V Appendices A Encoding/Decoding Simulations B Combined Use of ASN.1 and SDL

LTL and Beyond: Formal Languages for Reward Function Specification in Reinforcement Learning

Abstract: In Reinforcement Learning (RL), an agent is guided by the rewards it receives from the reward function. Unfortunately, it may take many interactions with the environment to learn from sparse rewards, and it can be challenging to specify reward functions that reflect complex reward-worthy behavior. We propose using reward machines (RMs), which are automata-based representations that expose reward function structure, as a normal form representation for reward functions. We show how specifications of reward in various formal languages, including LTL and other regular languages, can be automatically translated into RMs, easing the burden of complex reward function specification. We then show how the exposed structure of the reward function can be exploited by tailored q-learning algorithms and automated reward shaping techniques in order to improve the sample efficiency of reinforcement learning methods. Experiments show that these RM-tailored techniques significantly outperform state-of-the-art (deep) RL algorithms, solving problems that otherwise cannot reasonably be solved by existing approaches.

A Distributed Pi-Calculus

Abstract: Distributed systems are fast becoming the norm in computer science. Formal mathematical models and theories of distributed behaviour are needed in order to understand them. This book proposes a distributed pi-calculus called Dpi, for describing the behaviour of mobile agents in a distributed world. It is based on an existing formal language, the pi-calculus, to which it adds a network layer and a primitive migration construct. A mathematical theory of the behaviour of these distributed systems is developed, in which the presence of types plays a major role. It is also shown how in principle this theory can be used to develop verification techniques for guaranteeing the behavior of distributed agents. The text is accessible to computer scientists with a minimal background in discrete mathematics. It contains an elementary account of the pi-calculus, and the associated theory of bisimulations. It also develops the type theory required by Dpi from first principles. • First book on formal foundations of distributed computation • Accessible introduction to the theory of the pi-calculus, with many exercises • Contains many worked examples and over 70 exercises

Rex: Symbolic Regular Expression Explorer

Abstract: Constraints in form regular expressions over strings are ubiquitous. They occur often in programming languages like Perl and C#, in SQL in form of LIKE expressions, and in web applications. Providing support for regular expression constraints in program analysis and testing has several useful applications. We introduce a method and a tool called Rex, for symbolically expressing and analyzing regular expression constraints. Rex is implemented using the SMT solver Z3, and we provide experimental evaluation of Rex.

Church-Rosser Thue systems and formal languages

Abstract: Since about 1971, much research has been done on Thue systems that have properties that ensure viable and efficient computation. The strongest of these is the Church-Rosser property, which states that two equivalent strings can each be brought to a unique canonical form by a sequence of length-reducing rules. In this paper three ways in which formal languages can be defined by Thue systems with this property are studied, and some general results about the three families of languages so determined are studied.