D. T. Lee and A. K. Lin [2] proved that VERTEX-GUARDING and POINT-GUARDING are NP-hard for simple polygons. We prove that those problems are NP-hard for ortho-polygons, too.
First we give an overview about variants of visibility and related problems. Then we prove that some guarding and covering problems are NP-hard for ortho-polygons with holes, using a so-called vertex cover technique.
We show that given a simple Polygon P it is NP-hard to determine the smallest α ∈ [0, π] such that P can be illuminated by α-vertexlights, if we place exactly one α-vertexlight in each vertex of P.
For each vertex of a simple polygon P an integer valued weight is given. We consider the path p1, p2, ..., pk in P which is created according to the following strategy: p1 is a designated start vertex s and pi+1 is obtained by choosing the vertex with smallest weight among all vertices visible from pi and different from p1, p2, ..., pi. If there is no such vertex the path is finished. This path is called geometric lexicographic dead end (...) path. We shall prove the problem of determining whether a distinguished vertex t of P is on the geometric lexicographic dead end path or not to be P-complete. (shrink)
We consider the problem of quadrilaterizing an orthogonal polygon P, that is to decompose P into nonoverlapping convex quadrangles without adding new vertices. In this paper we present a CREW-algorithm for this problem which runs in O time using Θ processors if the rectangle decomposition of P is given, and Θ processors if not. Furthermore we will show that the latter result is optimal if the polygon is allowed to contain holes.
Jak czytamy na czwartej stronie okładki recenzowanej książki, „niezależna filozofia przyrody uznaje wyniki pozytywnej nauki oraz teorii nauki jako refleksji nad nią, zadaje jednak pytanie, czym jest owa przyroda, która jest przedmiotem techniczno-praktycznych i etyczno-praktycznych sytuacji". Książka składa się ze Wstępu i 6 nierównej objętości rozdziałów. Mimo, że nosi tytuł Naturphilosophie, sugerujący, że jest ona systematycznym wykładem filozofii przyrody, faktycznie stanowi wprowadzenie do tego rodzaju filozofii. Autor przedstawia w niej panorama współczesnych poglądów na filozofię, szczególnie na metafizyki, i przeprowadza gruntowną (...) ich krytykę. Ogólną tezą autora jest stwierdzenie, że nauki przyrodnicze programowo odcinają się od filozofii, odrzucając szczególnie pojęcie celowości. W praktyce jednak posługują się terminologią teleologiczną, w czym ujawnia się bądź ich niekonsekwencja, bądź ograniczenie. Autor jest zdania, że w poglądach wielu filozofujących fizyków kryje się niczym nie podbudowany platonizm, i jest skłonny przyznać w wielu przypadkach rację Arystotelesowi, którego w sposób nieuzasadniony współcześnie wielu kwestionuje. (shrink)
Summary A large survey of German and Israeli younger and older adolescents was conducted to reveal their opinions and attitudes towards violence and aggression, their personal engagement in aggressive and violent behaviors in and outside the school environment, their attitudes toward physical activity, their engagement in physical activity, and the linkage between physical activity engagement and conductance of violence and aggression. The findings point out that there are more similarities than differences between German and Israeli adolescents concerning violence and aggression (...) in and outside schools. No linkage between physical activity involvement and the extent of violent and/or aggressive acts is found. The findings pertaining adolescents’ opinions and attitudes toward aggression and violence and their behaviors in and outside school are encouraging. (shrink)
Transcendental Pragmatics and Discourse Ethics. Elements and Perspectives of Apel's Discourse-Philosophy. The author follows Apel's intellectual biography and shows the conception of a critique of meaning qua ‘reflection upon the discourse within the discourse’ to be the centre of Apel's language-pragmatic ‘Transformation of Philosophy’. Beginning with an explication of the situation of a speaker/thinker, especially of the situation of a philosophising speaker/thinker, Apel reconstructs a two fold apriori of communication: Every thought is situated within the context of a particular, historically (...) evolved, community of language and interaction. At the same time, however, the validity-claims of thoughts transcend the context of their origin towards an unlimited community of argumentation. On the basis of the first apriori Apel criticises the methodical solipsism as well as the objectivism of modern philosophy and theory of science. Drawing upon the second apriori he develops a universalist critique of meaning of relativism and contextualism. In the sixties and seventies Apel worked out a differentiated theory of the – more or less – communicatively cognizing humanities and set it apart from the theory of the causal-explanatory natural sciences, thus challenging the objectivism of a Theory of Unified Science. Building upon this work Transcendental Pragmatics, as developed by Apel and others, sets philosophy primarily two tasks: firstly, a internal reconstruction of argumentative discourse as the situation of speech and thought which seeks to elucidate the conditions of the meaningfulness, i. e. the presuppositions, of discourse. These presuppositions comprise, thus Apel with Habermas, the four validity-claims to intelligibility, sincerety/credibility, truth and normative rightness/legitimacy. Their moral content consists, thus Apel, not only in the recognition of the equality of all beings capable of discursive reasoning but also in their recognition of a co-responsibility for the realizability of discourses and of responsibility. The author argues that the existence of a co-responsibility of this kind is indisputable because the discursive claims to validity are intertwined with a set of ‘primordial promises of dialogue’. Only with the elucidation and explication of these promises can the reconstruction of the internal conditions of discourse be completed.The second task of a pragmatics of argumentation isthe strict resp. actual reflection of the thinker upon the presuppositions of the discourse in which he currently engages. This reflection has a Socratic character and can only be done in the form of discussion and debate with critics of the reconstruction. In this context, the author proposes a method of Socratic reflection upon the presuppositions of dialogue which suspends the usual, theoretically oriented, attitude of the scientist and the philosopher in favour of an actual reflective attitude. Within a dialogue with a sceptic who doubts one of the results of the internal reconstruction of dialogical presuppositions, say X, it is tested whether his doubt as to the unrestricted validity of X can be understood as a sincere contribution to the current dialogue or whether this particular sceptical thesis does not make sense, because it is incompatible with the role of a sincere participant of argumentation which, after all, the sceptic cannot refuse to claim for himself.Finally the author explains Apel's characterization of the tension between “Discourse and Responsibility”. In the course of discussions with Max Weber, Lawrence Kohlberg, Hans Jonas et al., Apel formulates and justifies an ethics of responsibility and gives an affirmative answer to the crucial question of whether the fulfilment of the moral obligations connected with the recognition of co-responsibility can be demanded within the non-dialogical circumstances of social reality. Apel's answer employs the idea of counter-strategies which are morally legitimate in virtue of their being worthy of argumentative consensus. (shrink)
Advancements in biological ageing research have shown that age-related diseases may be fought more effectively in the future by directly intervening into the ageing process. This prospect is associated with hopes for solving problems of demographic change. It also addresses raising awareness for complex ethical, legal and social issues that have hardly been a topic of discussion to date. Therefore, as the objective of our project, an interdisciplinary discourse module entitled “Ethics of Biogerontology” was developed to initiate a social debate (...) on the ethical, legal, and societal implications of biogerontology. The discourse module focuses on competences and argumentation skills and was developed with experts from relevant disciplines, e.g. biogerontology, social gerontology, philosophy, geriatrics, and medical ethics. Concepts of age and ageing are tightly interlinked with biogerontology and are as such relevant as teaching contents of the discourse module. The course module was tested in eight discourse teaching projects in research, medicine, and education in various partner institutions and evaluated based on an ethical competence model. This article describes the conception, including the learning objectives, of such a teaching course and the associated teaching contents. It also gives a justification for their selection. Finally, we summarize the results of the evaluation. (shrink)
Nach drei Semestern war ich 1951 von München nach Köln umgezogen, weil ich mit Wirtschaftswissenschaft Ernst machen wollte. Im wirtschaftswissenschaftlichen Seminar traf ich zum ersten Mal auf Hans Albert. Obwohl er ein halbes Jahrzehnt älter war als ich, arbeitete er als studentischer Amanuensis in der ökonomischen Bibliothek.
Was sind Emotionen, Gefühle, Affekte und Leidenschaften? Sprechen wir von erlebten und kommunizierten Gefühlszuständen oder von psychophysiologischen Erregungs- und Reaktionsmustern? Welche Rückschlüsse erlauben motorisches Verhalten und Ausdrucksverhalten auf unsere tatsächlichen Gefühle? Wie prägen soziale Prozesse und kulturelle Voraussetzungen das emotionale Erleben und Ausdrucksverhalten? Sollen wir unseren Gefühlen und Leidenschaften Grenzen setzen oder freien Lauf lassen? Müssen wir unsere Emotionen verbergen, oder dürfen wir Gefühle zeigen? Die Beiträge des Bandes vermitteln plastische Eindrücke von Emotionen im Wandel des Zeitgeists, konzentriert auf die (...) ausgeprägte Gefühlswelt von Mittelalter und Renaissance. Mediävistische Forschung erschließt uns literarische, bildliche und philosophisch-wissenschaftliche Konzepte von Emotionen sowie ihrer Bewertung aus vergangenen Jahrhunderten und regt an, sie auf Fragen unseres eigenen Lebens und unserer geschichtlichen Gegenwart zu beziehen. Mit Beiträgen von Dieter Birnbacher, Mechthild Dreyer, Martin Pickavé, Thomas Nisters, Isabelle Mandrella, Hans Hecker, Achim Landwehr, Hans Körner, Barbara Haupt, Irmgard Rüsenberg, Vittoria Borsò und Katharina Philipowski. (shrink)
Die mittelalterliche Formel „isti moderni“, „diese Modernen da“, drückt Distanz und Ablehnung aus. Denn Neugierde, die Suche nach Neuem, Modernem, kann Gewohntes, Etabliertes, Tradiertes bedrohen und konservative Reaktionen provozieren. Aber hat Neues, Modernes, nicht seinen eigenen Wert? Und verdankt sich nicht auch unsere Moderne in vielfältiger Weise den Erneuerungskonzepten des Mittelalters? Die Beiträge des Bandes präsentieren Erneuerungskonzepte in Mittelalter und Renaissance, die oft erst über Erneuerungskonflikte wirksam werden konnten. Zu Wort kommen Wissenschaftlerinnen und Wissenschaftler aus fünf Disziplinen: Vittoria Borsò (Romanistik), (...) Mechthild Dreyer (Philosophie) Barbara Haupt (Ältere Germanistik), Hans Hecker (Mittelalterliche Geschichte), Rudolf Hiestand (Mittelalterliche Geschichte), Maarten Hoenen (Philosophie), Willi Jung (Romanistik), Christoph Kann (Philosophie), Johannes Laudage † (Mittelalterliche Geschichte), Isabelle Mandrella (Philosophie) und Jürgen Wiener (Kunstgeschichte). (shrink)
Hans Reichenbach, a philosopher of science who was one of five students in Einstein's first seminar on the general theory of relativity, became Einstein's bulldog, defending the theory against criticism from philosophers, physicists, and popular commentators. This book chronicles the development of Reichenbach's reconstruction of Einstein's theory in a way that clearly sets out all of its philosophical commitments and its physical predictions as well as the battles that Reichenbach fought on its behalf, in both the academic and popular press. (...) The essays include reviews and responses to philosophical colleagues, such as Moritz Schlick and Hugo Dingler; polemical discussions with physicists Max Born and D. C. Miller; as well as popular articles meant to clarify aspects of Einstein's theories and set out their philosophical ramifications for the layperson. At a time when physics and philosophy were both undergoing revolutionary changes in content and method, this book is a window into the development of scientific philosophy and the role of the philosopher. (shrink)
I am greatly indebted to the German Fulbright Commission, and its Director, Dr Ulrich Littmann, for their generous support from September 1988 until February 1989, during which time I completed this paper. My gratitude also extends to the Zentralinstitut für sozialwissenschaftliche Forschung of the Free University of West Berlin, and its Directors Dr Dietrich Herzog and Dr Hans-Dieter Klingemann, who supplied me with both comfortable working conditions and a stimulating intellectual atmosphere.
This paper deals with Keynes’s distinction between entrepreneurship and speculation, regarding business people in general and especially investors’ behaviour. Based on Keynes’s thoughts about financial markets, it analyses how different motivations influence the decision-making process of investors and its consequences for stock markets and the real economy and clarifies that Keynes’s considerations are still useful for understanding contemporary developments and risks in the financial system. Furthermore, it points out that Keynes’s theories and policy recommendations should be understood in the context (...) of his moral considerations, especially relating to individual responsibility of investors. Finally, Keynes’s moral thoughts can be taken as a foundation for a contemporary approach to investors’ responsibility. (shrink)
