Some basic observations on Kelly's conjecture for graphs

AbstractP.J. Kelly first mentioned the possibility of determining a graph from subgraphs obtained by deleting several points. While such problems have received a great deal of attention in the case of deletions of single points, the problem for several points is virtually untouched. This paper contains some basic results on that problem, including the negative observation that for every k, there exist two non-isomorphic graphs with the same collection of k-point subgraphs

Tops-Only Domains

In this paper we consider the standard voting model with a finite set of alternatives A and n voters and address the following question : what are the characteristics of domains D that induce the property that every strategy-proof social choice function f : Dn -> A satisfying unanimity, has the tops-only property? We first impose a minimal richness condition which ensures that for every alternative a, there exists an admissible ordering where a is maximal. We identify conditions on D that are sufficient for strategy-proofness and unanimity to imply tops onlyness in the general case of n voters and in the special case, n = 2. We provide an algorithm for constructing tops-only domains from connected graphs with elements of A as nodes. We provide several applications of our results. Finally, we relax the minimal richness assumption and partially extend our results.Voting, social choice, tops-only domain

Instabilities and subharmonic resonances of subsonic heated round jets, volume 2

When a jet is perturbed by a periodic excitation of suitable frequency, a large-scale coherent structure develops and grows in amplitude as it propagates downstream. The structure eventually rolls up into vortices at some downstream location. The wavy flow associated with the roll-up of a coherent structure is approximated by a parallel mean flow and a small, spatially periodic, axisymmetric wave whose phase velocity and mode shape are given by classical (primary) stability theory. The periodic wave acts as a parametric excitation in the differential equations governing the secondary instability of a subharmonic disturbance. The (resonant) conditions for which the periodic flow can strongly destabilize a subharmonic disturbance are derived. When the resonant conditions are met, the periodic wave plays a catalytic role to enhance the growth rate of the subharmonic. The stability characteristics of the subharmonic disturbance, as a function of jet Mach number, jet heating, mode number and the amplitude of the periodic wave, are studied via a secondary instability analysis using two independent but complementary methods: (1) method of multiple scales, and (2) normal mode analysis. It is found that the growth rates of the subharmonic waves with azimuthal numbers beta = 0 and beta = 1 are enhanced strongly, but comparably, when the amplitude of the periodic wave is increased. Furthermore, compressibility at subsonic Mach numbers has a moderate stabilizing influence on the subharmonic instability modes. Heating suppresses moderately the subharmonic growth rate of an axisymmetric mode, and it reduces more significantly the corresponding growth rate for the first spinning mode. Calculations also indicate that while the presence of a finite-amplitude periodic wave enhances the growth rates of subharmonic instability modes, it minimally distorts the mode shapes of the subharmonic waves

Internalism and the Nature of Justification

There are many important dimensions of epistemic evaluation, one of which is justification. We don’t just evaluate beliefs for truth, reliability, accuracy, and knowledge, but also for justification. However, in the epistemological literature, there is much disagreement about the nature of justification and how it should be understood. One of the controversies that has separated the contemporary epistemological discourse into two opposing camps has to do with the internalism-externalism distinction. Whereas internalists defend certain core assumptions about justification from the pre-Gettier tradition, externalists generally think that the traditional conception is untenable and should be replaced. In this compilation thesis, I argue for, defend, and develop a particular brand of internalism, both in general and with respect to specific sources of justification. In papers 1 and 2, I defend a couple of well-known arguments for mentalism and accessibilism. Moreover, I also point out how prominent versions of these theses are vulnerable to serious problems (e.g., about over-intellectualization and vicious regresses). Part of my goal in the first couple of papers is to figure out what commitments the internalist should take on in order to avoid the externalist's objections, while at the same time receiving support from considerations that have motivated internalism in the past. In papers 3 and 4, I start from the assumption that mentalism is true and attempt to answer the following questions: 1) which non-factive mental states can play a justification-conferring role with respect to empirical belief? And 2) why does this set of states play the epistemic role it does? In response to question 1, I argue that all and only one's beliefs and perceptual experiences have justificatory relevance. In response to question 2, I argue that one's beliefs and perceptual experiences are one's strongly representational states, and that strongly representational states necessarily provide support to certain empirical propositions. Having done so, I then defend mentalism about scientific evidence from a couple of prominent objections in the recent literature. Lastly, in papers 5 and 6, I argue for a particular brand of internalism about testimonial and memorial justification and show how that position has a dialectical advantage over its main competitors

Advancing group epistemic practices in the resolution of interdisciplinary societal dilemmas

The present paper inquires whether a meticulous program designed to resolve Interdisciplinary Societal Dilemmas through dialogic argumentation advances epistemic practices. To delineate how epistemic practices are manifested in classroom discussions, we adopted the Actor-Network Theory (ANT), which explores the interactions and agencies of human and non-human actors. ANT analyses uncover the power these actors exert on each other and help recognize the networks that these actors create or dissolve. They also delineate how epistemic practices emerge and are shaped in these networks. We identified four epistemic practices in the discussions: (1) taking a reasoned position, (2) integrating knowledge from different disciplines, (3) weighing pros and cons before taking a complex position, and (4) role-playing in a democratic game. We show that the type of discourse developed in the program was mostly dialogic argumentation. In addition, we demonstrate how teachers often inhibit these advancements. Indeed, in the case of integrating knowledge from different disciplines, teachers’ role is central, but the emerged actors’ network is often non-dialogic. Moreover, we show how non-human actors shape the interactions in networks as well as the formation of knowledge and agency. We conclude that: (a) the design of activities for resolving interdisciplinary societal dilemmas provides many opportunities for advancing epistemic practices, (b) these practices are mostly advanced through dialogic argumentation, but (c) more efforts should be invested in affording interdisciplinary argumentation

The extent and relevance of instrumentalism, constructivism and critical realism in high school physical science textbooks : a critical study

Instrumentalism is a philosophy of science which holds that scientific theories are merely useful fictions for making computative predictions. Its pragmatic purpose of 'saving the appearances' downgrades the role of theory in science. Realists, on the other hand, take the implications of theories seriously. This study investigates the attributes of both instrumentalism and realism, taking theory as its point of departure. It is pointed out that constructivism is closely related to instrumentalism, both being forms of pragmatism. Since both tend to concoct and relinquish theories too easily, they tend to be relativist and subjectivist. It is therefore concluded that neither instrumentalism, nor constructivism, nor empiricism is sufficient for a rounded science education. What is needed is a type of realism which acknowledges both the empirical physical world 'out there' and the constructivist nature of scientific knowledge. The naive (empiricist) realism so prevalent in school science textbooks cannot do this. It is contended that critical realism, and especially that of Bernard Lonergan, can meet this requirement. Reality is more than what is given in sensory experience. Therefore, in order to help solve the problem of relativism and subjectivity inherent in constructivism, we need to revise our notion of reality and objectivity. Twenty-three selected British, American, South African, and African Third World high school physical science textbooks were examined in detail to determine the extent of an instrumentalist philosophy in them. They were subjected to several textual analyses, including one especially devised for this study. The results reveal that our high school physical science textbooks do indeed contain a high degree of instrumentalism. This study postulates that this instrumentalism may be used to help pupils move towards realism. However, this needs to be augmented by a full-blooded critical realist approach which takes theoretical entities seriously. One way of doing this is through the use of suitable material in the preface of every textbook. Not only should the dangers of instrumentalism (and naive constructivism) be pointed out, but the role of theory in science should be emphasised. This may be achieved by simulations to encourage growth of models and theories, historical case studies involving theory-development, and additional reading of scientists in action. Some examples of these are provided

MATHEMATICS VERSUS THE ARTS: A COMPARATIVE LOOK AT STUDENTS' ATTITUDES AND BELIEFS

Merged with duplicate record 10026.1/1937 on 15.02.2017 by CS (TIS)The words that students use to paint a picture of mathematics are very different from those which they use to describe their experiences in art and music. In the views of students, mathematics is pointless and repetitive while the arts are creative, relaxing and an expression of themselves. This thesis reports on the findings of a two part research project designed to investigate the attitudes of high school students when learning mathematics, art and music. The focus of this study was a comparative look at their confidence and enjoyment in learning these subjects. A questionnaire was designed and developed for use in a study of students in the United States and England (n = 1226). The intent of this questionnaire, which contained seven Likert-type questions and one open-ended response, was an in-depth look at the existence of confidence and enjoyment in learning mathematics, art and music. The results indicated that, the highest frequency of students in the mathematics group were confident in their ability in mathematics but did not enjoy learning it. This study also found, however, that there were very low percentages of students that were confident in art and music but did not enjoy learning them. Additionally there was a high frequency of students who had no confidence in art but did enjoy learning it compared to a low frequency of students in mathematics who were not confident but enjoyed learning it. To further explore these findings, repertory grid interviews were conducted on a selection of questionnaire participants from the United States (n = 42). Honey's method of content analysis was used to analyse the data. Among the differences found between students' confidence and enjoyment in learning mathematics compared to the arts were their perceptions of the routine nature of their daily lessons in mathematics versus their active, creative, personally engaging experiences while learning art and music

An exploration and validation of computer modeling of evolution, natural selection, and evolutionary biology with cellular automata for secondary students.

The Evolutionary Tool Kit, a new software package, is the prototype of a concept simulator providing an environment for students to create microworlds of populations of artificial organisms. Its function is to model processes, concepts and arguments in natural selection and evolutionary biology, using either Mendelian asexual or sexual reproduction, or counterfactual systems such as \u27paint pot\u27 or blending inheritance. In this environment students can explore a conceptual What if? in evolutionary biology, test misconceptions and deepen understanding of inheritance and changes in populations. Populations can be defined either with typological, or with populational thinking, to inquire into the role and necessity of variation in natural selection. The approach is generative not tutorial. The interface is highly graphic with twenty traits set as icons that are moved onto the \u27phenotypes\u27. Activities include investigations of evolutionary theory of aging, reproductive advantage, sexual selection and mimicry. Design of the activities incorporates Howard Gardner\u27s Theory of Multiple Intelligences. Draft of a teacher and student manual are included

Undergraduate representations of management and the possibilities of critical management education - the case of Portuguese management education.

Mann (2004: 208) identifies three components of emotional labour: 'The faking of emotion that is not felt and/or the hiding of emotion that is felt, and the performance of emotion management in order to meet expectations within a work environment. Nurses working in prison in England and Wales have a dual role; that of both carer and custodian. This thesis examines the emotional labour of nurses working in adult prisons who undertake a dual role in both caring and custody. A qualitative, reflexive methodology was adopted with a postmodern philosophical foundation. Phase one of the study involved semi-structured interviews with nine qualified nurses from three adult prisons: two male establishments and one female. In phase two of the study, two of these nine nurses entered into a supervisory relationship with the researcher. Monthly clinical supervision sessions were held with both nurses over six months. Findings from this study suggest that the nurse working in prison experiences emotional labour as a consequence of four key relationships: the relationship with the prisoner patient, the relationship with officer colleagues, and the relationship with the Institution; the fourth relationship centres on the contradictory discourses the nurse engages with internally, and is referred to as the 'intra-nurse' relationship. This relationship involves on-going internal dialogue between the two selves of the nurse: the professional self and the emotional 'feeling' self. In order to manage the emotion work inherent in prison work, it is suggested that the development of emotional intelligence through clinical supervision and reflective practice is of significant benefit to both health care and discipline staff