The paper studies applications of C*-algebras in geometric topology. Namely, a covariant functor from the category of mapping tori to a category of AF-algebras is constructed; the functor takes continuous maps between such manifolds to stable homomorphisms between the corresponding AF-algebras. We use this functor to develop an obstruction theory for the torus bundles of dimension 2, 3 and 4. In conclusion, we consider two numerical examples illustrating our main results., Igor Nikolaev., and Obsahuje seznam literatury
In this paper it is proved that an abelian lattice ordered group which can be expressed as a nontrivial lexicographic product is never affine complete.
Let $\Delta $ and $H$ be a nonzero abelian linearly ordered group or a nonzero abelian lattice ordered group, respectively. In this paper we prove that the wreath product of $\Delta $ and $H$ fails to be affine complete.
Identities for the curvature tensor of the Levi-Cività connection on an almost para-cosymplectic manifold are proved. Elements of harmonic theory for almost product structures are given and a Bochner-type formula for the leaves of the canonical foliation is established.
It is shown that under the name Mocis frugalis (F., 1775), considered to represent a widespread pest of graminaceous crops in the Eastern hemisphere and the Pacific, two species have been hitherto confused. Populations from Africa and Arabian Peninsula are described as Mocis proverai sp. n. The main characters which distinguish the African-Arabian M. proverai from M. frugalis of Asia and the Pacific are found in the genitalia, especially the configuration of the male vesica and female bursa copulatrix.
Afroaltica subaptera, a new genus and species of flea beetles (Chrysomelidae: Alticinae) from the eastern regions of southern Africa (Eastern Transvaal and Kwazulu-Natal), is described. Afroaltica gen. n. shows some similarities with the genus Dibolia Latreille, 1829 but it is easily distinguishable mainly by the simple-shaped apical spur of hind tibiae, not bifid. External habitus, scanning electronic micrographs of particular morphological features and line drawings of metafemoral spring and male and female genitalia of the new taxon are provided.
Based on the study of type material, two new genera of cestodes (Cyclophyllidea: Anoplocephalidae) are proposed for Paranoplocephala Lühe, 1910 sensu lato species from African rodents. Afrojoyeuxia gen. n., proposed for A. gundii (Joyeux, 1923) comb. n. from Ctenodactylus gundi (Rothmann) (Hystricomorpha: Ctenodactylidae), is characterized by a high length/width ratio of mature proglottids, longitudinally extensive testicular field positioned anterior to the female glands, an ovoid or subspherical cirrus-sac and a thick, conical cirrus. Hunkeleriella gen. n., proposed for H. dasymidis (Hunkeler, 1972) comb. n. from Dasymys incomtus (Sundevall) (Myomorpha: Muridae), differs from related genera mainly by its short (10-20 mm) and wide strobila and neck, unilateral genital pores (exceptionally with a few changes per strobila), the position of the genital pores (slightly anterior to the middle of proglottid margin) and initially tube-like early uterus (later reticulated). Parandrya Gulyaev et Chechulin, 1996, earlier suggested to be a junior synonym of Paranoplocephala, is considered to be a valid, independent genus. Evidence of non-monophyly and need for a taxonomic revision of Paranoplocephala sensu lato, as well as the phylogenetic position of A. gundii and H. dasymidis are discussed.