Formal Languages in Dynamical Systems

We treat here the interrelation between formal languages and those dynamical systems that can be described by cellular automata (CA). There is a well-known injective map which identifies any CA-invariant subshift with a central formal language. However, in the special case of a symbolic dynamics, i.e. where the CA is just the shift map, one gets a stronger result: the identification map can be extended to a functor between the categories of symbolic dynamics and formal languages. This functor additionally maps topological conjugacies between subshifts to empty-string-limited generalized sequential machines between languages. If the periodic points form a dense set, a case which arises in a commonly used notion of chaotic dynamics, then an even more natural map to assign a formal language to a subshift is offered. This map extends to a functor, too. The Chomsky hierarchy measuring the complexity of formal languages can be transferred via either of these functors from formal languages to symbolic dynamics and proves to be a conjugacy invariant there. In this way it acquires a dynamical meaning. After reviewing some results of the complexity of CA-invariant subshifts, special attention is given to a new kind of invariant subshift: the trapped set, which originates from the theory of chaotic scattering and for which one can study complexity transitions.Comment: 23 pages, LaTe

Demonstratives, referent identification and topicality in Wambon and some other Papuan languages

Abstract In Papuan languages like Wambon and Urim demonstrative forms are used both in contexts of referent identification, e.g. as demonstrative operators in noun phrases, and in topicality contexts, e.g. as topic markers with adverbial clauses and phrases, recapitulative clauses, new topic NPs and given topic NPs. Using notions from the Functional Grammar framework (Dik, 1989), I present a non-unified account of the demonstrative forms: helping the addressee to identify referents by giving deictic hints like ‘close to speaker’ and orienting the addressee about the topical cohesion of the discourse are two separate functional domains in language. This ‘two-domain’ hypothesis, which views the demonstrative forms as having two synchronically unrelated functions, explains the fact that in Wambon and Urim the demonstratives show important differences in form and behaviour depending on whether they are used for referent identification or for expressing topicality distinctions. The ‘two-domain’ hypothesis explains such formal differences but cannot explain the formal similarities between topic markers and demonstrative operators in Papuan languages like Wambon and Urim. To explain these formal similarities I suggest a diachronic development: in several Papuan languages topic markers developed from demonstrative operators. In the relatively well-documented Awyu-family of Papuan languages this process can be traced: in Wambon, the resumptive demonstrative pronoun- eve integrated in the preceding NP as a topic marker in stative clauses with a very transparant dichotomous topic-comment structure. In Korowai, also of the Awyu-family, the clitic -efè, function as a demonstrative operator and functions solely as a topic marker

Extracting Functionally Equivalent Object-Oriented Designs from Legacy Imperative Code

This research defines a methodology for automatically extracting functionally equivalent object-oriented designs from legacy imperative programs. The Parameter-Based Object Identification (PBOI) methodology is based on fundamental ideas that relate programs written in imperative languages such as C or COBOL to objects and classes written in object-oriented languages such as Ada 95 or C ++. Transformations have been developed that formalize the PBOI methodology and a formal proof is provided showing the extracted object-oriented design is functionally equivalent to the legacy imperative system. To focus the task of re-engineering, generic models of imperative programming languages and object-oriented programming languages have been developed. The formal transformations convert imperative subprograms represented in the Generic Imperative Model (GIM) into classes and objects represented in the Generic Object-Oriented Design Model (GOM). A taxonomy of imperative subprograms has also been developed which classifies all imperative subprograms into one of six categories. A proof-of-concept prototype has been developed and a 3000-line FORTRAN-77 system has been converted to an object-oriented design as a feasibility demonstration

Patrones léxicos compartidos en el dominio etnobiológico de las lenguas del Chaco: Análisis preliminar de patrones léxicos compartidos en el dominio etnobiológico. [The languages of the Gran Chaco from the perspective of lexical semantics: Preliminary analysis of shared lexical structures in the ethnobotanical domain].

With more than twenty languages belonging to six linguistic families, the Gran Chaco is a region of great interest for linguists dedicated to the typology and comparison of languages. However, while phonological and grammatical similarities have been the focus of most of these studies, the investigation of semantic patterns has so far played only a minor role. This work takes up the problem of the similarity and possible diffusion of features across the languages of the Chaco through the identification and analysis of shared lexico-semantic patterns in the ethnobiological vocabulary of sixteen languages of the region. Our research has been carried out with the assistance of specific annotation and data processing techniques using the EDICTORprogram, which allows, unlike classical methods, to work with a large corpus of digitally available data. The preliminary results of the analysis show a great similarity in the lexical motivation of the analyzed lexemes, mainly through formal patterns such as polysemy, derivation and composition, and semantic relations such as metaphor and metonym

Designing precise and flexible graphical modelling languages for software development

Model-driven approaches to software development involve building computerized models of software and the environment in which it is intended to operate. This thesis offers a selection of the author’s work over the last three decades that addresses the design of precise and flexible graphical modelling languages for use in model-driven software development. The primary contributions of this work are: • Syntropy: the first published object-oriented analysis and design (OOAD) method to fully integrate formal and graphical modelling techniques. • The creation of the Object Constraint Language (OCL) and its integration into the Unified Modeling Language (UML) specification. • The identification of requirements and mechanisms for increasing the flexibility of the UML specification. • The design and implementation of tools for implementing graphical Domain Specific Languages (DSLs). The starting point was the author’s experience with formal specification techniques contrasted with the lack of precision of published object-oriented analysis and design methods. This led to a desire to fully integrate these two topics – formal specification and object-orientation - into a coherent discipline. The Syntropy approach, created in 1994 by this author and John Daniels, was the first published complete attempt to do this. Much of the author’s subsequent published work concerns the Unified Modeling Language (UML). UML represented a welcome unification of earlier OOAD approaches, but suffered badly from inflexibility and lack of precision. A significant part of the work included in this thesis addresses the drawbacks of the UML and proposes improvements to the precision of its definition, including through the invention of Object Constraint Language (OCL) and its incorporation into the UML specification, and the consideration of UML as source material for the definition of Domain Specific Languages (DSLs). Several of the author’s published works in this thesis concern mechanisms for the creation of DSLs, both within a UML framework and separately

Functional real-time programming: the language Ruth and its semantics

Real-time systems are amongst the most safety critical systems involving computer software and the incorrect functioning of this software can cause great damage, up to and including the loss of life. If seems sensible therefore to write real-time software in a way that gives us the best chance of correctly implementing specifications. Because of the high level of functional programming languages, their semantic simplicity and their amenability to formal reasoning and correctness preserving transformation it thus seems natural to use a functional language for this task. This thesis explores the problems of applying functional programming languages to real-time by defining the real-time functional programming language Ruth. The first part of the thesis concerns the identification of the particular problems associated with programming real-time systems. These can broadly be stated as a requirement that a real-time language must be able to express facts about time, a feature we have called time expressibility. The next stage is to provide time expressibility within a purely functional framework. This is accomplished by the use of timestamps on inputs and outputs and by providing a real-time clock as an input to Ruth programs. The final major part of the work is the construction of a formal definition of the semantics of Ruth to serve as a basis for formal reasoning and transformation. The framework within which the formal semantics of a real-time language are defined requires time expressibility in the same way as the real-time language itself. This is accomplished within the framework of domain theory by the use of specialised domains for timestamped objects, called herring-bone domains. These domains could be used as the basis for the definition of the semantics of any real-time language

A survey of agent-oriented methodologies

This article introduces the current agent-oriented methodologies. It discusses what approaches have been followed (mainly extending existing object oriented and knowledge engineering methodologies), the suitability of these approaches for agent modelling, and some conclusions drawn from the survey

Bridging the Gap: Overcoming Barriers to Immigrant Financial Empowerment in Northwest Queens

Every day, immigrants in Northwest Queens struggle to find work, obtain legal status, and manage their finances. While immigrant consumers are an integral part of the New York City economy -- spending and saving money and paying taxes -- many face multiple barriers to financial empowerment. This means that many immigrants struggle to build the kind of wealth that could enable them to buy a home, pay for higher education, save for retirement, and lead to overall long-term economic stability and security. While many immigrant consumers do save money, many do not trust mainstream financial institutions because they do not provide linguistically or culturally competent services. Others are concerned about hidden or excessive fees. As a result many immigrant consumers utilize fringe financial services that tend to be predatory and exploitative