The Schur-Zassenhaus Theorem is one of the fundamental theorems of finite group theory. Here is its statement:Fact1.1 (Schur-Zassenhaus Theorem). Let G be a finite group and let N be a normal subgroup of G. Assume that the order ∣N∣ is relatively prime to the index [G:N]. Then N has a complement in G and any two complements of N are conjugate in G.The proof can be found in most standard books in group theory, e.g., in [S, Chapter 2, Theorem 8.10]. (...) The original statement stipulated one ofNorG/Nto be solvable. Since then, the Feit-Thompson theorem [FT] has been proved and it forces eitherNorG/Nto be solvable. (The analogous Feit-Thompson theorem for groups of finite Morley rank is a long standing open problem).The literal translation of the Schur-Zassenhaus theorem to the finite Morley rank context would state that in a groupGof finite Morley rank a normal π-Hall subgroup (if it exists at all) has a complement and all the complements are conjugate to each other. (Recall that a groupHis called aπ-group, where π is a set of prime numbers, if elements ofHhave finite orders whose prime divisors are from π. Maximal π-subgroups of a groupGare called π-Hall subgroups. They exist by Zorn's lemma. Since a normal π-subgroup ofGis in all the π-Hall subgroups, if a group has a normal π-Hall subgroup then this subgroup is unique.)The second assertion of the Schur-Zassenhaus theorem about the conjugacy of complements is false in general. As a counterexample, consider the multiplicative group ℂ* of the complex number field ℂ and consider thep-Sylow for any primep, or even the torsion part of ℂ*. LetHbe this subgroup.Hhas a complement, but this complement is found by Zorn's Lemma (consider a maximal subgroup that intersectsHtrivially) and the use of Zorn's Lemma is essential. In fact, by Zorn's Lemma, any subgroup that has a trivial intersection withHcan be extended to a complement ofH. Since ℂ* is abelian, these complements cannot be conjugated to each other. (shrink)

One of the purposes of this paper is to prove a partial Schur-Zassenhaus Theorem for groups of finite Morley rank.Theorem 2.Let G be a solvable group of finite Morley rank. Let π be a set of primes, and let H ⊲ G a normal π-Hall subgroup. Then H has a complement in G.This result has been proved in [1] with the additional assumption thatGis connected, and thought to be generalized in [2] by the authors of the present article. Unfortunately in (...) the last section of the latter paper there is an irrepairable mistake. Here we give a new proof of the Schur-Zassenhaus Theorem using the results of [2] up to the last section and a new result that we are going to state below.The second author has shown in [11] that a nilpotentω-stable group is the central product of a divisible subgroup and a subgroup of bounded exponent, generalizing a well-known result of Angus Macintyre about abelian groups [8]. One could ask a similar question for solvable groups: are they a product of two subgroups, one divisible, one of bounded exponent? One is allowed to be hopeful because of the well-known decomposition of the connected solvable algebraic groups over algebraically closed fields as the product of the unipotent radical and a torus. (shrink)

Cauchy’s contribution to the foundations of analysis is often viewed through the lens of developments that occurred some decades later, namely the formalisation of analysis on the basis of the epsilon-delta doctrine in the context of an Archimedean continuum. What does one see if one refrains from viewing Cauchy as if he had read Weierstrass already? One sees, with Felix Klein, a parallel thread for the development of analysis, in the context of an infinitesimal-enriched continuum. One sees, with Emile Borel, (...) the seeds of the theory of rates of growth of functions as developed by Paul du Bois-Reymond. One sees, with E. G. Björling, an infinitesimal definition of the criterion of uniform convergence. Cauchy’s foundational stance is hereby reconsidered. (shrink)

A construction of the real number system based on almost homomorphisms of the integers $\mathbb {Z}$ was proposed by Schanuel, Arthan, and others. We combine such a construction with the ultrapower or limit ultrapower construction to construct the hyperreals out of integers. In fact, any hyperreal field, whose universe is a set, can be obtained by such a one-step construction directly out of integers. Even the maximal (i.e., On -saturated) hyperreal number system described by Kanovei and Reeken (2004) and independently (...) by Ehrlich (2012) can be obtained in this fashion, albeit not in NBG . In NBG , it can be obtained via a one-step construction by means of a definable ultrapower (modulo a suitable definable class ultrafilter). (shrink)

We examine Paul Halmos’ comments on category theory, Dedekind cuts, devil worship, logic, and Robinson’s infinitesimals. Halmos’ scepticism about category theory derives from his philosophical position of naive set-theoretic realism. In the words of an MAA biography, Halmos thought that mathematics is “certainty” and “architecture” yet 20th century logic teaches us is that mathematics is full of uncertainty or more precisely incompleteness. If the term architecture meant to imply that mathematics is one great solid castle, then modern logic tends to (...) teach us the opposite lesson, namely that the castle is floating in midair. Halmos’ realism tends to color his judgment of purely scientific aspects of logic and the way it is practiced and applied. He often expressed distaste for nonstandard models, and made a sustained effort to eliminate first-order logic, the logicians’ concept of interpretation, and the syntactic vs semantic distinction. He felt that these were vague, and sought to replace them all by his polyadic algebra. Halmos claimed that Robinson’s framework is “unnecessary” but Henson and Keisler argue that Robinson’s framework allows one to dig deeper into set-theoretic resources than is common in Archimedean mathematics. This can potentially prove theorems not accessible by standard methods, undermining Halmos’ criticisms. (shrink)

Cauchy's sum theorem is a prototype of what is today a basic result on the convergence of a series of functions in undergraduate analysis. We seek to interpret Cauchy’s proof, and discuss the related epistemological questions involved in comparing distinct interpretive paradigms. Cauchy’s proof is often interpreted in the modern framework of a Weierstrassian paradigm. We analyze Cauchy’s proof closely and show that it finds closer proxies in a different modern framework.

COSTA, Alexandre da. Fundamentos da bioética: estudo sobre o pensamento de Hugo Tristram Engelhardt Jr. FERREIRA, Amauri Carlos. O imaginário religioso e modos de vida urbana: experiência e memória da Juventude Católica em Belo Horizonte – MG, anos 80. GONÇALVES, Davidson Sepini. O Panóptico de Jeremy Bentham: por uma leitura utilitarista. GÓIS, Aurino José. Parque Municipal de Belo Horizonte: público, apropriações e significados. FARIA, Paulo Antônio Couto. Teologia no limiar da filosofia: a modernidade e o encontro fé e razão (...) na obra de Henrique Cláudio de Lima Vaz. (shrink)

TOPOGRAPHICAL MISSIONS ΤΟ LATO I (2005-2007): A CRITICAL ANALYSIS OF THE PLAN BY J. DEMARGNE AND V. SEYK (1901) In the years 2005 and 2007 the site of Lato in Crete was the object of three new topographical and geomorphological study campaigns. The works carried out over the entire site permitted in particular the analysis of the only to date available complete plan of the city, that of J. Demargne and the architect V. Seyk undertaken in 1900. The objectif was (...) to establish its documentary interest and limits in use, and thus better prepare new measurements and guide renewed field work. To do this, it was first necessary (I) to retrace the history of previous graphic documentation, (II) to analyse the work of J. Demargne and V. Seyk, so as (III) to gauge its value against the standards of current research, and (IV) to establish its interest in terms of the cultural resource management of the site. A second paper to appear in BCH will develop, on basis of a new documentation, the urban and morphological analysis of the remains of Lato. (shrink)

O objetivo deste artigo é propor, de modo simples e saudável, uma releitura transformadora na relação entre os ministérios ordenados e a missão leiga, sobretudo no tocante à espiritualidade laical como colaboração eclesial. Com efeito, desde o tempo de Jesus, o protagonismo leigo, como cooperador à evangelização sempre foi ressaltado e muito bem aproveitado pelo Mestre; dessa forma, nota-se o quanto a Igreja carece hoje dessa ajuda primordial. Não por menos, o Concilio Vaticano II, no decreto Apostolicam Actuositatem, diz que (...) o fiel leigo é indispensável á missão da Igreja. Assim, entre tantas orientações, o mesmo decreto convoca a renovar e valorizar o ardor missionário com o apostolado leigo no interior da Igreja. Nesse sentido, é urgente a aplicação do pedido solicitado no Concílio Vaticano II para os tempos atuais, visando à sua concretização e não ficar somente em uma longínqua teoria. É nesta óptica, que a V CELAM, realizada em Aparecida, enfatiza mais uma vez a indispensabilidade do leigo como colaborador profícuo na missão eclesial. Por fim, vemos em muito a realização exemplar de muitos fiéis leigos batizados em seu exercício de ministros não-ordenados que oferecem subsídios riquíssimos para santificar a vida na Igreja. (shrink)

La polémique entre V. Soloviev et L. Lopatine met en lumière les recherches de la philosophie russe sur son mode propre de compréhension du Moi. Pour Soloviev, on ne peut attribuer au sujet de la conscience en tant que tel une réalité autre que phénoménologique. Lopatine propose une variante, proche de Leibniz, selon laquelle le Moi est une conscience subjective, présente aux différents niveaux du développement spirituel. Cette interprétation est reprise et développée, dans une certaine mesure, par N. Losski. G. (...) Chpet tire un bilan de la discussion, en posant le caractère « communautaire » [ obščnost ’] particulier du Moi, qui se réalise non par la « généralisation » [ obobščenie ] mais par la « communication » [ obščenie ]. (shrink)

This is a long-awaited reprint of the major work of the late Alexandre Koyré, one of the greatest masterpieces of the history of Western philosophy. The early nineteenth century saw a revival of Boehme studies but even the commentaries of Franz von Baader could not be substituted for a scholarly synthesis of Boehme's thought. Boehme is a universe of his own, and only the immense learning of a man like Koyré, with his rare ability to synthesize and clarify, could (...) have done justice to him. Through and beyond the rich and baroque splendor of the cosmic poetry of the Dawn of the Mysterium Magnum, we see the birth of the modern philosophical spirit. What Boehme offers us is a philosophy of freedom, and, despite the modesty of his comparisons, Koyré does not fail to show how all this anticipates the greatest Idealistic systems.--M. J. V. (shrink)

The famous middle Byzantine alchemical manuscript Marcianus graecus 299 contains annotations from the late Byzantine period, most prominently in its opening quire. This article examines a text on the very first page of the manuscript, a text written in a late Byzantine Greek script, but in a language other than Greek. A number of words in this undeciphered text can be correlated with Arabic technical vocabulary that would also have been used in other Islamicate languages such as Persian and Ottoman (...) Turkish. Certain features such as accentuation on the final syllables of words make Turkish or Persian the most likely candidates. (shrink)

This article examines the dedicatory epigram of the earliest and most important witness to the Greek alchemical corpus, the tenth-century manuscript donated by Cardinal Bessarion to the Republic of Venice, Biblioteca Nazionale Marciana MS gr. 299, as a window onto the cultural coordinates of the manuscript’s middle Byzantine readers. Scrutiny of the epigram’s meter, language, literary conventions, and the handwriting of the scribe who copied it into the manuscript point to a tenth-century date not only for the manuscript but also (...) for the epigram itself and make it possible to situate the epigram, and with it the alchemical manuscript that contains it, within the mainstream of middle Byzantine elite culture. (shrink)

Originally published in English in 1973. This volume traces the development of the revolution which so drastically altered manâes view of the universe in the sixteenth and seventeenth centuries. The "astronomical revolution" was accomplished in three stages, each linked with the work of one man. With Copernicus, the sun became the centre of the universe. With Kepler, celestial dynamics replaced the kinematics of circles and spheres used by Copernicus. With Borelli the unification of celestial and terrestrial physics was completed by (...) abandonment of the circle in favour the straight line to infinity. (shrink)

This article explores the relation between the concept of symmetry and its formalisms. The standard view among philosophers and physicists is that symmetry is completely formalized by mathematical groups. For some mathematicians however, the groupoid is a competing and more general formalism. An analysis of symmetry that justifies this extension has not been adequately spelled out. After a brief explication of how groups, equivalence, and symmetries classes are related, we show that, while it’s true in some instances that groups are (...) too restrictive, there are other instances for which the standard extension to groupoids is too un restrictive. The connection between groups and equivalence classes, when generalized to groupoids, suggests a middle ground between the two. *Received July 2007. †To contact the authors, please write to: Alexandre Guay, UFR Sciences et Techniques, Université de Bourgogne, 9 Avenue Alain Savary, 21078 Dijon Cedex, France; e‐mail: alexandre[email protected] ; or to Brian Hepburn, Department of Philosophy, University of British Columbia, 1866 Main Mall E370, Vancouver, BC, Canada V6T 1Z1; e‐mail: [email protected]. (shrink)

В монографии рассматривается соотношение индивидуальных и универсальных начал в праве как эффективное средство решения многих правовых проблем, как руководство в законодательной и судебной деятельности.

Le futur est un thème clé des pères fondateurs des sciences sociales. Marx, Durkheim, Weber abordent la question du Progrès et des évolutions de long terme des sociétés. Ces travaux mettent fin au monopole de la métaphysique sur le futur et ouvrent la porte aux premières enquêtes.Aujourd’hui, il est possible d’utiliser les méthodes des sciences sociales pour participer de manière renouvelée à l’exploration du futur, en s’attachant aux visions non expertes. Pour ce faire, quelle meilleure entrée que celle de la (...) mobilité spatiale? Elle est une activité quotidienne et un symbole du Progrès, au travers des innovations techniques qui ont accompagné son essor lors des deux derniers siècles.Afin d’interroger les visions profanes du futur par le biais de la mobilité spatiale, 53 entretiens qualitatifs ont été conduits. Les résultats obtenus permettent de comprendre les visions du futur de la mobilité et les formes d’évolution du temps qui habitent les individus contemporains, qu’elles soient progressistes, fatalistes, ou bien rhizomatiques. Ces visions concernent le réchauffement climatique, la fin du pétrole et de la voiture. Par le biais de ces visions profanes, l’enquête couvre ainsi les enjeux les plus saillants des sociétés contemporaines. (shrink)

Infinitary languages are used to prove that any strong isomorphism of substructures of isomorphic structures can be extended to an isomorphism of the structures. If the structures are models of a theory that has quantifier elimination, any isomorphism of substructures is strong. This theorem is a partial generalization of Steinitz’s theorem for algebraically closed fields and has as special case the analogous theorem for differentially closed fields. In this note, we announce results which will be proved elsewhere. DOI: 10.5007/1808-1711.2011v15n1p107.

En 1785, Alexander Cozens publie un court traité, un manuel à l’usage des jeunes peintres les invitant à utiliser la tache et le hasard comme préalable à la composition de paysages. En 1969, Jean Messagier élabore une technique, « le Gel », pour parfaire un certain nombre de ses compositions. Cet article s’articule autour d’une mise en perspective de ces deux expériences. Il vise à porter un regard sur les rapports que l’art du paysage entretient avec l’abstraction, avant même qu’elle (...) n’existe ou au cœur de son plein épanouissement et propose de réfléchir à l’utilité ou la vacuité d’un tel débat. Il brosse une histoire rapide de l’utilisation de la tache et du hasard dans l’histoire de la création et enfin, il présente la position singulière de Jean Messagier au sein de l’histoire de la peinture abstraite et propose d’engager une étude plus fine de l’œuvre de ce dernier. (shrink)