Van Emden Research Articles

The recursion-theoretic complexity of the semantics of predicate logic as a programming language

The coupling of resolution techniques for automatic theorem proving with what is termed the procedural interpretation of logic (Kowalski 1979) has resulted in efforts to implement predicate logic as a programming language. These efforts have already resulted in the language PROLOG. The semantics of predicate logic as a programming language have been formulated with an orientation toward the precedural interpretation of logic in van Emden and Kowalski (1976) and Apt and van Emden (1980). The predicate logic core of PROLOG is a restriction to universally quantified Horn sentences with atomic conclusions, so-called definite clauses, and therefore prevents the user from fully expressing logical negation. In the procedural interpretation of logic, a logic program is regarded as its and only if'' version of which half is explicitly presented. The precise definition of this and only if version is given in Clark (1980). The interpretations of a logic program are then restricted to the Herbrand models of the and only if,' version of the program, and the formula F is Herbrand valid in logic program P iff F is valid in all such Herbrand interpretations of P. Although the user does not have negation available the control features of PROLOG do allow the user to have a useful but still limited form of negation: to infer ~A from a proof of the unprovability of A. This is sound, as we shall see, in the procedural interpretation of logic. Our purpose here is to use a connection between the semantics of predicate logic as a programming language and the well-studied theory of inductive definability to given a measure to the incompleteness of the negation as failure rule for proving Herbrand valid negations of formulas, and then to show that the negation as failure rule is very highly incomplete in the sense of the measure. Moreover, the general problem of deciding whether a formula is Herbrand

Practical Identification of the Females of Five Species ofAtherigonaRondani (Diptera, Muscidae) in Kenya

Abstract Morphological characters are described and illustrated to permit identification of the females of five species of Atherigona (A. soccata Rondani, A. conigera van Emden, A. trapezia van Emden, A. laevigata (Loew) and A. (Acritochaetal orientalis Schiner). The importance of being able to identify females of various species of Atherigona in ecological studies is discussed.

A MODIFIED CLIP CAGE FOR USE WITH APHIDS AND OTHER SMALL INSECTS

Experimental ecologists have frequently used cages to facilitate their understanding of ecological systems. This has been particularly true of ecologists studying aphids and other small insects, and a variety of cage designs have been described, ranging from small screened tents to sleeve cages to clip cages (see Adams and van Emden, 1972). The purpose of this note is to describe a modified clip cage design that is suitable for use on irregular cylindrical surfaces as well as on leaves.

F.-L. Roland Belanger, Damedieus: the religious context of the French epic. The Loherain Cycle viewed against other early French epics

Journal Article F.-L. Roland Bélanger, Damedieus: the religious context of the French epic. The Loherain Cycle viewed against other early French epics Get access Damedieus: the religious context of the French epic. The Loherain Cycle viewed against other early French epics. By F.-L. Roland Bélanger. (Histoire des Idées et Critique Littéraire,No. 152). Genève: Droz. 1975. xxviii + 299 pp. 60 Sw.F. W. G. Van Emden W. G. Van Emden Reading Search for other works by this author on: Oxford Academic Google Scholar French Studies, Volume XXXIII, Issue suppl, January 1980, Pages 524–525, https://doi.org/10.1093/fs/XXXIII.suppl.524 Published: 01 January 1980

REVIEWS

REVIEWS Get access A Guide to Studies on the ‘Chanson de Roland’. By J. J. DUGGAN. (Research Bibliographies and Checklists, 15.) London: Grant & Cutler. 1977. 133 PP.£5.40. W. G. VAN EMDEN W. G. VAN EMDEN READING Search for other works by this author on: Oxford Academic Google Scholar French Studies, Volume XXXIV, Issue 3, July 1980, Pages 316–317, https://doi.org/10.1093/fs/XXXIV.3.316 Published: 01 July 1980

The use of Hoare's method of program verfification for the quicksort algorithm

Using the Quicksort Algortihm, given by van Emden, an analysis is made how Hoare's method of program verification can be applied to already existing programs. Changes to these programs become necessary to adopt them to the proving method and to the existing axioms. The interdependencies between these changes and the verification method are discussed and conclusions are draw about the applicability of Hoare's Methods for proving already existing programs.

SYMPOSIUM: PEST-PLANT RELATIONSHIPS Some Characteristics of Phytophagous Insects and their Hosts in New Zealand

Previous symposia on insect-plant associations have been held in London in 1971 (van Emden 1973), and in Boulder Colorado in 1973 (Gilbert 1975). I will not attempt to summarise or discuss the subjects covered exhaustively by Rothschild, Southward, and Harris (in van Emden 1973) or by Feeny (in Gilbert 1975) but will discuss some characteristics of the New Zealand biota, and also try to relate some of the anomalies in our biota to the rather engaging arms race theory expounded most explicitly by Feeny (1975).

Book Reviews

Combined Science 1 G. GREEN, K. PETFORD, A. SHORT and D.WALKER Pupils' book, 128 pp., illustrated, £1.25. Teachers' guide, 81 pp., illustrated, £1.95. London: John Murray, 1975. Reviewed by Stuart Newton Pupils' Attitudes to Science: a review of research M. B. ORMEROD and D. DUCKWORTH 150 pp. Windsor: NFER Publishing Company, 1975. £3.50. Reviewed by Don Ryman Pest Control and its Ecology Studies in Biology No. 50 H. F. VAN EMDEN 60 pp., illustrated. London: Edward Arnold, 1975. £1.90 boards, 95p paper. Reviewed by Colin Wood Robinson Plant Cell Structure and Metabolism J. L. HALL, T. J. FLOWERS and R. M. ROBERTS 426 pp., illustrated. London: Longman, 1974. £4.95. Reviewed by J. H. Duffus The Evolution of IBP E. B. WORTHINGTON (Ed.) 268 pp., illustrated. Cambridge: Cambridge University Press, 1975. £10.50. Reviewed by A. D. Berrie Biochemistry of Antimicrobial Action T. J. FRANKLIN and G. A. SNOW Second edition. 224 pp., illustrated. London: Chapman and Hall, 1975. £7.00 boards, £3.95 paper. Reviewed by A. I. Tiffin Pollutants and Animals—a factual perspective F. MORIARTY 140 pp., illustrated. London: George Allen and Unwin, 1975. £5.65 Reviewed by Paul Rogers Living Clocks in the Animal World M. F. BENNETT 221 pp., illustrated. Springfield, 111.: Charles C. Thomas, 1974. $11.75. Reviewed by R. P. Dales Anatomy, Physiology and Hygiene J. K. RAEBURN and H. A. RAEBURN Fourth edition. 375 pp., illustrated. London: John Murray, 1975. £1.95. Reviewed by A. W. Le Serve A Zoo in Your Room R. CARAS 96 pp., illustrated. London: Harcourt Brace Jovanovich, 1975. £1.65. Reviewed by Richard Cansdale Plant Cell Biology—An Ultrastructural Approach B. E. S. GUNNING and M. W. STEER 278 pp., illustrated. London: Edward Arnold, 1975. £2.75. Reviewed by John F. Duffus Experimental Work in Biology No. 7: Respiration and Gaseous Exchange D. G. MACKEAN Reviewed by Cecily Gale General Ecology—Biocenology-Hydrobiology Volume 1 L. I. DROZHILOVA (Ed.) 109 pp., illustrated. Boston, Mass.: G. K. Hall, 1974. $21.00. Reviewed by A. D. Berrie Biochemistry LUBERT STRYER 877 pp., illustrated. San Francisco and Reading: W. H. Freeman, 1975. £9.40. Reviewed by J. H. Parish Photosynthesis M. A. TRIBE, M. R. ERAUT and R. K. SNOOK Cambridge University Press

The effect of leaf excision on the performance of Myzus persicae and Brevicoryne brassicae in relation to the nutrient treatment of the plants

AbstractTwo groups of brussels sprout plants of one variety given different fertilizer treatments proved ‘resistant’ and ‘susceptible’ to both Myzus persicae and Breicoryrie brassicae, as measured by aphid mean relative growth rate. The hypothesis that leaf disc would fail to reflect differences in ‘nutritionallybased’ plant resistance was confirmed with B.brussicue but not M.persicae. Both aphids grew more slowly on discs than leaves of ‘susceptible’ plants; the reverse tendency showed on ‘resistant’ material. Total:(, amino nitrogen proved poorly correlated with aphid performance. Previously published (van Emden & Bashford, 1971) equations relating individual amino acids to aphid performance gave a better fit to the results, but still failed to account for the reduced performance of the aphids on ‘susceptible’ discs.

Review: "Studies in Biology". No. 49, Esturaine Biology, by R. S. K. Barnes; "Studies in Biology". No. 50, Pest Control and Its Ecology, by Helmut F. van Emden; and "Studies in Biology". No. 51, the Ecology of Small Mammals, by M. J. Delaney

Review: <i>"Studies in Biology". No. 49, Esturaine Biology</i>, by R. S. K. Barnes; <i>"Studies in Biology". No. 50, Pest Control and Its Ecology</i>, by Helmut F. van Emden; and <i>"Studies in Biology". No. 51, the Ecology of Small Mammals</i>, by M. J. Delaney

Pest Control and its Ecology. The Institute of Biology's Studies in Biology No. 50.Helmut F. van Emden

<i>Pest Control and its Ecology. The Institute of Biology's Studies in Biology No. 50.</i>Helmut F. van Emden

Review. Structural arithmetic metaphor in the Oxford 'Roland'. Bulatkin, Eleanor W.

Journal Article REVIEWS Get access Structural Arithmetic Metaphor in the Oxford ‘Roland’. By ELEANOR WEBSTER BULATKIN. Columbus: Ohio State University Press. 1972. xiv + 115 pp. $8.00. W. G. VAN EMDEN W. G. VAN EMDEN READING Search for other works by this author on: Oxford Academic Google Scholar French Studies, Volume XXIX, Issue 4, October 1975, Pages 442–443, https://doi.org/10.1093/fs/XXIX.4.442 Published: 01 October 1975

The Effect of Stand Size and Vegetational Background on the Colonization of Cruciferous Plants by Herbivorous Insects

The spatial dispersion of resources is a major factor in the population dynamics of many insects. This is especially true of herbivorous species which utilize ephemeral host plants, or which must leave the host during the life cycle and subsequently rediscover it. In such situations the pattern of colonization by insects will be determined by the interaction between the plants' spatial dispersion and the insects' behaviour. This investigation attempts to answer two questions. (1) What is the effect of host plant plot size on the numbers and kinds of herbivores that occupy the stand, and (2) how does the background of a stand (i.e. the presence or absence of other vegetation) influence its colonization ? Size and background of stands are not the only aspects of host plant spatial dispersion that affect insects. Others are plant density (Dethier 1959a, b; Pimentel 1961a; Davis 1966; Way & Heathcote 1966; Clark et al. 1967; A'Brook 1968, 1973; Heathcote 1969), distance from other stands (Janzen 1968, 1970) and proximity to other environmental features including overwintering sites and alternate hosts (Wolfenbarger 1940; Moreton 1945; Wright & Ashby 1946; van Emden 1965; Lewis 1969; Johnson 1969). The former two were chosen for investigation because these characteristics in natural vegetation and agricultural crops are the most consistently different. Crops are usually grown in patches which are larger and contain fewer other kinds of plants than natural patches of their wild relatives. The prevalence of insect outbreaks on cultivated plants is related in part to these differences (Pimentel 1961b; van Emden 1964; Smith 1972; Tahvanainen & Root 1972; Root 1973). Furthermore, the same factors are important in the biological control of weeds by insects. An insect's response to large concentrations of its host plant determines its ability to control the host population, and the colonization behaviour of the species is one of the determinants of the equilibrium densities of insect and host (Huffaker 1962; Janzen 1970). Despite recognition of the importance of plant spatial dispersion for insects (Huffaker 1962; Johnson 1969), there have been few attempts to document either responses of individual insect species or the size and composition of the entire herbivore fauna in stands of different sizes. Douwes (1968) found that the female geometrid moth, Cidaria albulata L., alighted more frequently on hosts (Rhinanthus sp.) in dense clumps than on scattered hosts. In the vicinity of larger patches of Rhinanthus the flight path was shorter and the moth changed direction more frequently, apparently in response to higher concentration of the host's odour. Away from these patches, the female made longer, faster flights. Thus the behavioural pattern of Cidaria albulata caused it to remain in or near larger patches of Rhinanthus. * Present address: ENVL, Stockton State College, Pomona, N.J. 08240, U.S.A.

Review. A literary history of France. The Middle Ages. Fox, J.

Journal Article REVIEWS Get access A Literary History of France. The Middle Ages. By JOHN FOX. London: Benn; New York: Barnes and Noble. 1974. xx + 380 pp. £5.00. W. G. VAN EMDEN W. G. VAN EMDEN READING Search for other works by this author on: Oxford Academic Google Scholar French Studies, Volume XXIX, Issue 2, April 1975, Pages 177–178, https://doi.org/10.1093/fs/XXIX.2.177 Published: 01 April 1975

Observations on the Behavior of Zoospores of a Saprolegnia Species

(1975). Observations on the Behavior of Zoospores of a Saprolegnia Species. Mycologia: Vol. 67, No. 2, pp. 425-428.

Physiology of Tree Resistance to Insects

The economic impact of insect damage to trees is so great that research efforts aimed at controlling insect pests are easily justified and research accomplishments are readily measured. As a result of past research on many insect-tree combinations, progress has been made towards the discovery and development of control methods including insecticides, silvicultural techniques, attractants, and the use of parasites, predators, and diseases. Remarkably little use has been made of tree resistance for control of pest populations despite the fact that this is generally regarded as the ideal method ( lO, 66). Although tree losses are being reduced by nongenetic means and will continue to be reduced as methods are refined, insect damage to our forest and ornamental trees remains enormous. Genetic methods have proved successful in combating many crop insects and offer as much or more potential for alleviating damage to trees (77). Development of host resistance as an effective tool for long-term control of insect pests requires a multidisciplinary approach by �eneticists, physiologists, and en­ tomologists. Unfortunately, one or more of the disciplines is usually missing and this has partially contributed to the general lack of progress in this area. This has recently been discussed by Philogene (79) with regard to the need for plant physiolo­ gists to work on host-insect relationships, but it is equ.ally true with respect to forest geneticists. Stark (105) covered several facets of tree resistance to insects in his 1965 review of forest entomology. The book edited by van Emden (25) also contains much information pertinent to the topic. The objective of the following discussion is to critically examine the concept of tree resistance to insects and to review our knowl­ edge of the physiological mechanisms involved in resistance. Hopefully, this may at least stimulate more discussion of the problem and perhaps productive research among the three disciplines.

SHAKESPEARE AND THE FRENCH PYRAMUS AND THISBE TRADITION, OR WHATEVER HAPPENED TO ROBIN STARVELING'S PART?

Journal Article SHAKESPEARE AND THE FRENCH PYRAMUS AND THISBE TRADITION, OR WHATEVER HAPPENED TO ROBIN STARVELING'S PART? Get access W. G. VAN EMDEN W. G. VAN EMDEN Reading Search for other works by this author on: Oxford Academic Google Scholar Forum for Modern Language Studies, Volume XI, Issue 3, July 1975, Pages 193–204, https://doi.org/10.1093/fmls/XI.3.193 Published: 01 July 1975

REVIEWS

REVIEWS A Literary History of France. The Middle Ages. By JOHN FOX. London: Benn; New York: Barnes and Noble. 1974. xx + 380 pp. £5.00. W. G. VAN EMDEN W. G. VAN EMDEN READING Search for other works by this author on: Oxford Academic Google Scholar French Studies, Volume XXIX, Issue 2, April 1975, Pages 177–178, https://doi.org/10.1093/fs/XXIX.2.177 Published: 01 April 1975

Another look at Charlemagne's dreams in the Chanson de Roland

Journal Article ANOTHER LOOK AT CHARLEMAGNE'S DREAMS IN THE CHANSON DE ROLAND Get access W. G. VAN EMDEN W. G. VAN EMDEN LANCASTER Search for other works by this author on: Oxford Academic Google Scholar French Studies, Volume XXVIII, Issue 3, July 1974, Pages 257–271, https://doi.org/10.1093/fs/XXVIII.3.257 Published: 01 July 1974

BOOK REVIEWS

Book reviewed in this article:H. F. VAN EMDEN (Ed.) 1973: Insect/Plant Relationships. Symposia of the Royal Entomological Society of LondonJ. G. Rodriguez (Ed.): Insect and Mite NutritionF. Zumpt: The Stomoxyine Biting Flies of the World. DipteraA. D. Lowe (Ed.): Perspectives in Aphid Biology.