A Basis for Interactive Schema Merging

We present a technique for merging the schemas of heterogeneous databases that generalizes to several different data models, and show how it can be used in an interactive program that merges Entity-Relationship diagrams. Given a collection of schemas to be merged, the user asserts the correspondence between entities and relationships in the various schemas by defining "isa" relations between them. These assertions are then considered to be elementary schemas, and are combined with the elementary schemas in the merge. Since the method defines the merge to be the join in an information ordering on schemas, it is a commutative and associative operation, which means that the merge is defined independent of the order in which schemas are presented. We briefly describe a prototype interactive schema merging tool that has been built on these principles. Keywords: schemas, merging, semantic data models, entity-relationship data models, inheritance 1 Introduction Schema merging is the proble..

A Survey of Preservice Teachers in Regards to Their Attitudes and Perceptions of Science Fiction Literature and its Use in the Classroom

In 1957 at the University of Chicago, Robert Heinlein asserted that through science fiction humanity can wonder upon important questions without causing harm to the real world. Through such speculative experiments science fiction can warn against dangerous solutions, urge toward better solutions. Science fiction joyously tackles the real and pressing problems of our race, wrestles with them, never ignores them—problems which other forms of fiction cannot challenge. For this reason I assert that science fiction is the most realistic, the most serious, the most significant, the most sane and healthy and human fiction being published today. (Davenport, 1959). Preservice teachers enrolled in the education program at a large metropolitan university were surveyed to determine if they had preconceived notions about science fiction, if they would use science fiction within their classrooms and if science fiction would be available to the students in their classrooms. Also explored was if these future educators believed science fiction was too complex for English language learners and students with exceptionalities. Analysis of this survey revealed that although most preservice teachers believe science fiction literature has value within the classroom and they planned to use it at least part of the time, about one in five believed the concepts and themes were too complex for English language learners and students with exceptionalities. The researcher of this study hopes the information contained in this study can help educators encourage students to read science fiction as well as provide the educators with a resource of science fiction literature book titles which are grade level and ability level appropriate for their students

Types With Extents: On Transforming and Querying Self-Referential Data-Structures (Dissertation Proposal)

The central theme of this paper is to study the properties and expressive power of data-models which use type systems with extents in order to represent recursive or self-referential data-structures. A standard type system is extended with classes which represent the finite extents of values stored in a database. Such an extended type system expresses constraints about a database instance which go beyond those normally associated with the typing of data-values, and takes on an important part of the functionality of a database schema. Recursion in data-structures is then constrained to be defined via these finite extents, so that all values in a database have a finite representation. The idea of extending a type system with such classes is not new. In particular [2] introduced a type system and data models equivalent to those used here. However such existing work focuses on the expressive power of systems which allow the dynamic creation of recursive values, while we are concerned more with the properties of querying and manipulating databases containing known static extensions of data-values

Formal Models for Concurrent Communicating Systems

This report was originally written to fulfill in part the requirements of the author\u27s WPE examinations, part of the qualifying examinations for the University of Pennsylvania\u27a Computer Science Ph.D program. The report first introduces CCS and uses it to illustrate various features of established methods of modelling concurrent, communicating systems. The report then goes on to describe and investigate two new models for such systems: The Chemical Abstract Machine, a simple yet predominant in most models for such systems; and the π-calculus, a calculus similar in many respects to CCS, but able to model mobile processes and other, more difficult phenomena

Transforming Databases with Recursive Data Structures

This thesis examines the problems of performing structural transformations on databases involving complex data-structures and object-identities, and proposes an approach to specifying and implementing such transformations. We start by looking at various applications of such database transformations, and at some of the more significant work in these areas. In particular we will look at work on transformations in the area of database integration, which has been one of the major motivating areas for this work. We will also look at various notions of correctness that have been proposed for database transformations, and show that the utility of such notions is limited by the dependence of transformations on certain implicit database constraints. We draw attention to the limitations of existing work on transformations, and argue that there is a need for a more general formalism for reasoning about database transformations and constraints. We will also argue that, in order to ensure that database transformations are well-defined and meaningful, it is necessary to understand the information capacity of the data-models being transformed. To this end we give a thorough analysis of the information capacity of data-models supporting object identity, and will show that this is dependent on the operations supported by a query language for comparing object identities. We introduce a declarative language, WOL, based on Horn-clause logic, for specifying database transformations and constraints. We also propose a method of implementing transformations specified in this language, by manipulating their clauses into a normal form which can then be translated into an underlying database programming language. Finally we will present a number of optimizations and techniques necessary in order to build a practical implementation based on these proposals, and will discuss the results of some of the trials that were carried out using a prototype of such a system

The Relationship of Small Mammal Species to Habitat Variables in West-Central Georgia and East-Central Alabama

The objective of this investigation was to assess the impact of environmental variables upon small mammal species distribution in 60 plots on Fort Benning, Muscogee and Chattahoochee Counties, Georgia and Russell County, Alabama. The small mammal fieldwork was carried out in December of 1994 through January of 1995. The vegetation was inventoried in June through October of 1995. During this period, 235 small mammals were trapped in a total of 5950 trap nights. A total of 10 small mammal species and 234 plant species were identified. The small mammal species abundance\u27s were determined by using snap trapping along the plot transect. The responses of the Blarina carolinensis, Cryptotis parva, Oryzomys palustris, Reithrodontomys humulis, Peromyscus gossypinus, Peromyscus polionotus, Ochrotomys nuttalli, Sigmodon hispidus, Neotoma floridana, and Mus musculus with respect to the the sand to clay ratio, percent slope, elevation, distance to water, number of burns, number of evergreen and deciduous species, number of grass species, number of forb species, canopy cover, understory, and percent bareground cover were evaluated and analyzed using a direct gradient analysis technique termed Canonical Correspondence Analysis (CCA). To evaluate the response of specific species with high abundance, a second analysis was performed to include only Reithrodontomys humulis, Peromyscus gossypinus, Peromyscus polionotus, and Sigmodon hispidus. The modified analysis was consistent with the first unmodified analysis with the exception of Sigmodon. The modified analysis showed that the most important habitat characteristic for Sigmodon was a low degree of understory. Perturbations to important microhabitat characteristics due to training or land management practices would change the distributions of several species. The four most important environmental variables with respect to how the small mammals responded to them were understory, canopy cover, the number of deciduous species, and percent bareground cover. Changes in land management practices like decreasing the frequency of burning or training practices such as the removal of vast tracts of trees would change the distribution of small mammals species

Living to Ride: A Sociological Study of Freeriders in Missoula, Montana

Kosky, Marlana M., M.A., Fall 2007 Sociology Living to Ride: A Sociological Study of Freeriders in Missoula Montana Chairperson: Robert W. Balch This paper is an ethnographic description of The Safety Team, a group of freeriders frequenting the Bike Doctor in Missoula Montana. Information about this faction of freeriding’s social world is revealed using the members’ own words and experiences as data. This study is meant to explore the significance of bike riding to the members of Missoula’s freeride “scene,” including its effect on their beliefs, values, and ethics. Qualitative methods are used including participant-observation structured within the theoretical framework of symbolic interactionism. Relationships within freeriding are explored, as are associations between this group and members of the larger society such as land managers. The history of mountain biking and freeriding are explored and issues within Missoula’s local backdrop are described. The riders’ perspectives on their sport and its image is described while the future of freeriding is speculated upon using extreme sport predecessors with commonalities such as skateboarding and snowboarding

The Horse Course Restart Program - Analysis of an Initial Data Set.

Large numbers of people with non-psychotic mental health problems have little benefit from usual interventions. We present initial, uncontrolled data on the efficacy of an equine-assisted programme across a number of domains for people with a range of psychological and behavioural problems who have had no or inadequate benefit from traditional approaches

Semantics of Database Transformations

Database transformations arise in many different settings including database integrations, evolution of database systems, and implementing user views and data-entry tools. This paper surveys approaches that have been taken to problems in these settings, assesses their strengths and weaknesses, and develops requirements on a formal model for specifying and implementing database transformations. We also consider the problem of insuring the correctness of database transformations. In particular, we demonstrate that the usefulness of correctness conditions such as information preservation are hindered by the interactions of transformations and database constraints, and the limited expressive power of established database constraint languages. We conclude that more general notions of correctness are required, and that there is a need for a uniform formalism for expressing both database transformations and constraints, and reasoning about their interactions. Finally we introduce WOL, a declarative language for specifying and implementing database transformations and constraints. We briefly describe the WOL language and its semantics, and argue that it addresses many of the requirements of a formalism for dealing with general database transformations

Facilitating Transformations in a Human Genome Project Database

Human Genome Project databases present a confluence of interesting database challenges: rapid schema and data evolution, complex data entry and constraint management, and the need to integrate multiple data sources and software systems which range over a wide variety of models and formats. While these challenges are not necessarily unique to biological databases, their combination, intensity and complexity are unusual and make automated solutions imperative. We illustrate these problems in the context of the Human Genome Database for Chromosome 22 (Chr22DB), and describe a new approach to a solution for these problems, by means of a deductive language for expressing database transformations and constraints