Theory of Automata

Runtime monitoring is a widely used approach to ensure code safety. Several
implementations of formal monitors have been proposed in the literature, and these differ
with respect to the set of security policies that they are capable of enforcing. In this survey,
we examine the evolution of knowledge regarding the issue of precisely which security
policies monitors are capable of enforcing.We identify three stages in this evolution. In the
first stage, we discuss initial limits on the set of enforceable properties and various ways in
which this set can be extended. The second stage presents studies that identify constraints
to the enforcement power of monitors. In the third stage, we present a final series of studies
that suggest various alternative definitions of enforcement, which specify both the set of
properties the monitors can enforce as well as the manner by which this enforcement is
provided.

Soliton automata are the mathematical models of certain possible molecular switching devices. Both from theoretical and practical point of view, it is a central question to describe soliton automata with constant external edges. Extending a result of Dassow and Jürgensen, we characterize soliton automata in this special case.

While monadic second-order logic is a prominent logic for specifying languages of finite words, it lacks the power to compute quantitative properties, e.g. to count. An automata model capable of computing such properties are weighted automata, but logics equivalent to these automata have only recently emerged. We propose a new framework for adding quantitative properties to logics specifying Boolean properties of words. We use this to define Quantitative Monadic Second-Order Logic (QMSO). In this way we obtain a simple logic which is equally expressive to weighted automata. We analyse its evaluation complexity, both data and combined complexity, and show completeness results for combined complexity. We further refine the analysis of this logic and obtain fragments that characterise exactly subclasses of weighted automata defined by the level of ambiguity allowed in the automata. In this way, we define a quantitative logic which has good decidability properties while being resonably expressive and enjoying a simple syntactical definition. I. INTRODUCTION Using logics as specification languages for properties of finite and infinite words or trees has a long history in computer science. Of particular importance in this context is Monadic Second-Order Logic (MSO), the extension of first-order logic by quantification over sets of positions in the input word (see e.g. [23], [10]). The prominence of MSO as logic over words has many causes: It is a very expressive and yet simple logic in which many properties can be expressed very naturally. In fact, Büchi's classical theorem [6] states that a language is recognisable by a finite state automaton if, and only if, it is definable in MSO. Hence, MSO can define precisely the regular languages and provides an elegant specification mechanism for regular properties. Furthermore , the proof of the theorem is algorithmic which implies that MSO formulas can effectively be compiled into finite automata which can then be run in linear time on any input word. Finally, MSO has very good decidability properties and standard problems such as satisfiability and therefore equivalence and containment of formulas are decidable over finite words. While MSO is an elegant and highly successful mechanism for specifying word languages, there are many ap

Although Philip Mirowski’s work has been profoundly influential in fields as diverse as economics, history of science, political theory, and even literary studies, it is less well-known in the emerging complex of fields which are sometimes referred to as “digital studies,” meaning all the fields that directly analyze the social, cultural, and political-economic impact of the computer. This is unfortunate enough from the perspective of political economy, since Mirowski’s writings on neoliberalism resonate strongly with some of the most incisive political-economic work in digital studies. It is even more unfortunate when Mirowski’s work is seen at a larger scale, wherein he emerges as one of the most serious thinkers anywhere regarding the myriad impacts of the computer, especially but not only on intellectual practice over the last hundred or so years. From his writings on the neoliberal grounding of concepts like “open science,” to his recent “fictionalist” account of the function of information in economics, and especially in his thorough and uncompromising analysis of the computer and its metaphorics across a variety of disciplines in Machine Dreams, Mirowski’s work constitutes an unmatched source of critical thought that deserves to be far more widely disseminated among scholars of the digital.

Microscopic traffic flow models are a class of scientific models of vehicular traffic dynamics. Here, we attempted to establish an experimental platform for mimicking microscopic traffic flow models at microscopic dimensions. We achieved this, by monitoring the flow of micro-sized particles transported by the motile cells of living microorganisms. Some researchers have described the cells of protozoan species as "swimming neurons" or "swimming sensory cells" applicable to biological micro-electro- mechanical systems or micro-biorobotics. Therefore these cells, in a controlled environment, may form a good model system for bio-implementable cellular automata for traffic simulation. The living cells of the Paramecium species including those of green paramecia (Paramecium bursaria), actively migrate towards a negatively charged electrode when exposed to an electric field. This type of cellular movement is known as galvanotaxis. P. bursaria was chosen as amodel organismsince the ideal micro-vehicles required for micro-particle transport must have a particular particle packing capacity within the cells. The present study establishes that the movement of cells with or without the loading of microspheres (φ, 9.75 μm) can be controlled on a two-dimensional plane under strict electrical controls. Lastly, implementation of microchips equipped with optimally sized micro-flow channels that allow the single-cell traffic of swimming P. bursaria was proposed for further studies and mathematical modeling.

In this paper, we present a new framework of runtime security policy enforcement. Building on previous studies, we examine the enforcement power of monitors able to transform their target’s execution, rather than simply accepting it if it is valid, or aborting it otherwise. We bound this ability by a restriction stating that any transformation must preserve equivalence between the monitor’s input and output. We proceed by giving examples of meaningful equivalence relations and identify the security policies that are enforceable with their use. We also relate our work to previous findings in this field. Finally, we investigate how an a priori knowledge of the target program’s behavior would increase the monitor’s enforcement power.

We discuss how to increase and simplify the understanding of the equivalence relations between machine models and/or language representations of formal languages by means of the animation tool SAGEMoLiC. Our new educational tool permits the simulation of the execution of models of computation, as many other animation systems do, but its philosophy goes further than these of the usual systems since it allows for a true visualization of the key notions involved in the formal proofs of these equivalences. In contrast with the proposal of previous systems, our approach to visualize equivalence theorems is not a simple "step by step animation" of specific conversion algorithms between computational models and/or grammatical representations of formal languages, because we make emphasis on the key theoretical notions involved in the formal proofs of these equivalences.

Monitoring is a powerful security policy enforcement paradigm that allows the execution of a potentially malicious software by observing and transforming it, thus ensuring its compliance with a user-defined security policy. Yet some restrictions must be imposed on the monitor's ability to transform sequences for the enforcement to be meaningful. The intuition behind our model is that the monitor should be bounded to output a sequence that both respects the desired security property and preserves  key elements of the execution's semantics.  An approximation of the sequence is executed rather than an equivalent one. This approximation must preserve the essential behavior of the sequence as intended by the user. In this paper, we propose a framework to express and study such a restriction based on partial orders.  We give several examples of real-life security policies and propose monitors capable of enforcing these properties. We then turn to the question of comparing several monitors enforcing the same security property.

A crucial issue in the Software Cost Estimation area that has attracted the interest of software project managers is the selection of the best prediction method for estimating the cost of a project. Most of the prediction techniques estimate the cost from historical data. The selection of the best model is based on accuracy measures that are functions of the predictive error, whereas the significance of the differences can be evaluated through statistical procedures. However, statistical tests cannot be applied easily by non-experts while there are difficulties in the interpretation of their results. The purpose of this paper is to introduce the utilization of a visualization tool, the Regression Error Characteristic curves in order to compare different prediction models easily, by a simple inspection of a graph. Moreover, these curves are adjusted to accuracy measures appeared in Software Cost Estimation literature and the experimentation is based on two well-known datasets.

Soliton circuits are among the most promising alternatives for molecular electronic devices based on the design of molecular level conventional digital circuits. In order to capture the logical and computational aspects of these circuits, a mathematical model called soliton automaton was introduced by Dassow and Jürgensen in 1990.

In this paper, we study the data interoperability problem of web services in terms of XML schema compatibility. When Web Service A sends XML messages to Web Service B, A is interoperable with B if B can accept all messages from A. That is, the XML schema R for B to receive XML instances must be compatible with the XML schema S for A to send XML instances, i.e., A is a subschema of B. We propose a formal model called Schema Automaton (SA) to model W3C XML Schema (XSD) and develop several algorithms to perform different XML schema computations. The computations include schema minimization, schema equivalence testing, subschema testing, and subschema extraction. We have conducted experiments on an e-commerce standard XSD called xCBL to demonstrate the practicality of our algorithms. One experiment has refuted the claim that the xCBL 3.5 XSD is backward compatible with the xCBL 3.0 XSD. Another experiment has shown that the xCBL XSDs can be effectively trimmed into small subschemas for specific applications, which has significantly reduced the schema processing time.

In this paper, we propose new models and algorithms to perform practical computations on W3C XML Schemas, which are schema minimization, schema equivalence testing, subschema testing and subschema extraction. We have conducted experiments on an e-commerce standard XSD called xCBL to demonstrate the e?ectiveness of our algorithms. One experiment has refuted the claim that the xCBL 3.5 XSD is compatible with the xCBL 3.0 XSD. Another experiment has shown that the xCBL XSDs can be effectively trimmed into small subschemas for specific applications, which has significantly reduced schema processing time.

Partially lossy queue monoids (or plq monoids) model the behavior of queues that can forget arbitrary parts of their content. While many decision problems on recognizable subsets in the plq monoid are decidable, most of them are undecidable if the sets are rational. In particular, in this monoid the classes of rational and recognizable subsets do not coincide. By restricting multiplication and iteration in the construction of rational sets and by allowing complementation we obtain precisely the class of recognizable sets. From these special rational expressions we can obtain an MSO logic describing the recognizable subsets. Moreover, we provide similar results for the class of aperiodic subsets in the plq monoid. 2012 ACM Subject Classification Theory of computation → Algebraic language theory, Theory of computation → Models of computation, Information systems → Data structures

Soliton automata are the mathematical models of certain possible molecular switching devices called soliton circuits. Both from theoretical and practical point of view, it is a central question to describe soliton automata with a single external vertex. Extending a result of Dassow and Jürgensen, we characterize nondeterministic automata in this special case.

Abstract This paper describes a non-conventional method for compiling (phonological or morpho-syntactic) context restriction (CR) constraints into non-deterministic automata in finite-state tools and surface parsing systems. The method reduces any CR into a simple one that constraints the occurrences of the empty string and represents right contexts with co-determististic states.

While collecting data from network traffic, one can create classifiers that recognize threats, anomalies, or other events. The set of labelled Net Flow records collecting traffic statistics is a very useful source of decision rules that classify the records. These rules can be created automatically using machine learning techniques. However, the classifiers learned on such records may recognise only past events and cannot recognise current events, because not all data were collected. A deterministic finite automaton is a classifier that can recognise events online. However, the automaton is hard to project in case of complex issues. The paper proposes how to convert a decision tree into a deterministic finite automaton. The decision tree learns how to recognise threats using the collected data. Consequently, the set of decision rules is transformed into a finite automaton that can detect events before the full complement of data is collected. The method is limited to small trees, but can solve real problems. As an example, the detection of the TCP SYN flood attack is presented. For that example, the created automaton has the same high accuracy ratio as the decision tree, but can take decisions over three times faster.

Theory of splicing is an abstract model of the recombinant behaviour of DNAs. In a splicing system, two strings to be spliced are taken from the same set and the splicing rule is from another set. Here we propose a generalised splicing (GS) model with three components, two strings from two languages and a splicing rule from third component. We propose a generalised self assembly (GSA) of strings. Two strings u1xv1 and u2xv2 self assemble over x and generate u1xv2 and u2xv1. We study the relationship between GS and GSA. We study some classes of generalised splicing languages with the help of generalised self assembly.

The fourth of eight chapters from "Grace and Gravity: Architectures of the Figure." The argumentation builds on terminology introduced in the first three chapters, the most important being the phased structure of the figure: prefiguration, figuration, and transfiguration. Also, the earlier developed interdependence of motion and standstill that we encounter both in beauty and in grace, is here expanded in the relationship between the mineral, animal, and vegetal.

En esta corta entrada regresaremos al vídeo juego autómata, la máquina cinemática, el cómo interpretaban las aventuras conversacionales y gráficas el lenguaje humano. Seguiremos con los viejos discos plásticos LASER DISC y CD-ROM medios de los primeros filmes interactivos, finalizaremos como Façade uno de los grandes sobrevalorados en este blog, aun cuando el primero es ciertamente ELIZA de 1966 por Joseph Weizenbaum.

This paper outlines an application of iterated version of generalised sequential crossover of two languages (which in some sense, an abstraction of the crossover of chromosomes in living organisms) in studying some classes of the newly proposed generalised splicing (GS) over two languages. It is proved that, for X, Y ∈ {F IN, REG, LIN, CF, CS, RE}, Σ ∈ F IN , the subclass of generalized splicing languages namely GS(X, Y, Σ), (which is a subclass of the class GS(X, Y, F IN )) is always regular.

RÉSUMÉ. Nous présentons une implémentation flexible et originale de la distance d’édition : la composition filtrée, un type particulier de composition de deux machines à états finis au travers d’un filtre qui modélise l’ensemble des opérations d’édition valides. Le filtre est un transducteur pondéré ou une cascade de transducteurs pondérés. Il est obtenu par compilation de règles de réécriture qui profitent d’un nouveau concept défini dans notre bibliothèque de machines à états finis: le marqueur de règles, un symbole qui n’appartient pas à l’alphabet utilisé, mais est inséré dans une règle de réécriture afin d’identifier un phénomène et d’en suivre l’évolution. Les marqueurs désambiguïsent et facilitent l’expression de conditions et de contraintes. La méthode est illustrée dans le cadre de la correction des mots hors vocabulaire.

ABSTRACT. We present an original and flexible implementation of the edit-distance: the filtered composition, a special kind of composition of two finite-state machines through a filter that models all valid edit-operations. The filter is either a weighted transducer or a cascade of weighted transducers. It is built from weighted rewrite rules that take advantage of a new concept defined in our finite-state framework: the rules’ marker, a symbol that does not belong to the alphabet in use, but is inserted into a rewrite rule in order to mark a phenomenon and to track its evolution. Markers disambiguate and make it easy to express conditions and constraints. The method is illustrated on the task of correcting out-of-vocabulary words.

MOTS-CLÉS : distance d’édition, composition filtrée, marqueurs de règles, correction orthographique.