Genetic variation and acid tolerance in the Nemouridae (Insecta: Plecoptera)

An electrophoretic survey of sixteen enzyme loci in nine of the eleven British Nemouridae (Insecta: Plecoptera) was carried out in order to assess their systematic relationships and to determine the level of genetic variation in these primitive insects. [Continues.

Mersenne numbers

These notes have been issued on a small scale in 1983 and 1987 and on request at other times. This issue follows two items of news. First, WaIter Colquitt and Luther Welsh found the 'missed' Mersenne prime M110503 and advanced the frontier of complete Mp-testing to 139,267. In so doing, they terminated Slowinski's significant string of four consecutive Mersenne primes. Secondly, a team of five established a non-Mersenne number as the largest known prime. This result terminated the 1952-89 reign of Mersenne primes. All the original Mersenne numbers with p < 258 were factorised some time ago. The Sandia Laboratories team of Davis, Holdridge & Simmons with some little assistance from a CRAY machine cracked M211 in 1983 and M251 in 1984. They contributed their results to the 'Cunningham Project', care of Sam Wagstaff. That project is now moving apace thanks to developments in technology, factorisation and primality testing. New levels of computer power and new computer architectures motivated by the open-ended promise of parallelism are now available. Once again, the suppliers may be offering free buildings with the computer. However, the Sandia '84 CRAY-l implementation of the quadratic-sieve method is now outpowered by the number-field sieve technique. This is deployed on either purpose-built hardware or large syndicates, even distributed world-wide, of collaborating standard processors. New factorisation techniques of both special and general applicability have been defined and deployed. The elliptic-curve method finds large factors with helpful properties while the number-field sieve approach is breaking down composites with over one hundred digits. The material is updated on an occasional basis to follow the latest developments in primality-testing large Mp and factorising smaller Mp; all dates derive from the published literature or referenced private communications. Minor corrections, additions and changes merely advance the issue number after the decimal point. The reader is invited to report any errors and omissions that have escaped the proof-reading, to answer the unresolved questions noted and to suggest additional material associated with this subject

Semantic networks

AbstractA semantic network is a graph of the structure of meaning. This article introduces semantic network systems and their importance in Artificial Intelligence, followed by I. the early background; II. a summary of the basic ideas and issues including link types, frame systems, case relations, link valence, abstraction, inheritance hierarchies and logic extensions; and III. a survey of ‘world-structuring’ systems including ontologies, causal link models, continuous models, relevance, formal dictionaries, semantic primitives and intersecting inference hierarchies. Speed and practical implementation are briefly discussed. The conclusion argues for a synthesis of relational graph theory, graph-grammar theory and order theory based on semantic primitives and multiple intersecting inference hierarchies

Rigid designation, scope and modality

Thesis. 1979. Ph.D.--Massachusetts Institute of Technology. Dept. of Linguistics and Philosophy.MICROFICHE COPY AVAILABLE IN ARCHIVES AND HUMANITIES.Includes bibliographical references.by George E. Smith.Ph.D

Logical presupposition : a re-appraisal of the concept and revision of the theory

PhD ThesisThis dissertation is a defence of a logical approach to presupposition. In it (1) I enumerate, by way of apologia, some fundamental assumptions underlying both antagonistic and protagonistic treatments of such an approach, and argue that they are conceptually unnecessary, methodologically untoward, and/or logically contradictory. Most saliently, (a) I demonstrate the conceptual and logical contradiction in the view that presuppositional logic might be compatible with (or even imply) an ambiguity of natural language negation, (b) I provide a critique of the now traditional disassociation of the problems of presupposition-definition and presupposition- projection, (c) I provide a critique of the view that presuppositional logic -might be compatible with (or imply) logical trivalence. (2) In the light of a discussion of the conceptual distinction, I propose logical criteria for the distinction between a three-valued logic and a two-valued logic with truth-value gaps. (3) I demonstrate that, by these criteria, the standard (Strawsonian) Definition of Presupposition (SLDP) induces a trivalent logic. (4) I present a distinct (but comparable) revised logical definition of presupposition (RLDP)showing that it induces a system that conforms to the proposed criteria for a two-valued logic with truth-value gaps. (5) By showing that the several problems associated with the SLDP do not arise (are 'solved') in the framework of the RLDP I show (a) that the problems encountered by the SLDP stem more or less directly from its trivalence and (b) that the facts of presupposition-projection are (and should be) immanent in the concept (and hence the definition) of presupposition itself, rather than represented as properties of logical functors. I also show that the revised definition reveals an unsuspected connection between compound counter-examples and simple counter-examples to the SLDP