Archivio della ricerca dell'Università di Modena e Reggio Emiliahttps://iris.unimore.itIl sistema di repository digitale IRIS acquisisce, archivia, indicizza, conserva e rende accessibili prodotti digitali della ricerca.Tue, 07 Dec 2021 16:31:01 GMT2021-12-07T16:31:01Z101481A note on four-manifolds with free fundamental groupshttp://hdl.handle.net/11380/450966Titolo: A note on four-manifolds with free fundamental groups
Abstract: We study the homotopy decomposition problem for closed connected 4-manifolds with free fundamental groups. For this we apply obstruction theory and give a detailed description of Whitehead's exact sequence for the named class of manifolds.
Wed, 01 Jan 1997 00:00:00 GMThttp://hdl.handle.net/11380/4509661997-01-01T00:00:00ZA splitting theorem for homotopy equivalent 4-manifoldshttp://hdl.handle.net/11380/450996Titolo: A splitting theorem for homotopy equivalent 4-manifolds
Abstract: We prove a decomposition theorem for closed connected homotopy equivalent smooth four-manifolds, which partially extends a recent result of Curtis, Freedman, Hsiang and Stong, Invent. Math., 123 (1996), to the non-simply connected case. Then we study the question of when a homotopy equivalence between closed smooth 4-manifolds is homotopic to a topological homeomorphism. In particular, we obtain a new proof of the well-known uniqueness of closed aspherical smooth 4-manifolds with good fundamental groups.
Wed, 01 Jan 1997 00:00:00 GMThttp://hdl.handle.net/11380/4509961997-01-01T00:00:00ZAlgebraic properties of surgery obstruction groupshttp://hdl.handle.net/11380/450971Titolo: Algebraic properties of surgery obstruction groups
Abstract: In questo articolo si riassumono le definizioni e le principali proprieta`dei gruppi di ostruzione con decorazione di tipo LS e LP. Si stabiliscono nuove relazioni fra questi gruppi e si descrivono le proprieta`delle mappe naturali fra differenti gruppi con decorazione. Si costruiscono varie successioni spettrali, contenenti questi gruppi con decorazione, e si studiano la loro connessione con le successioni spettrali in K-teoria per certe estensioni quadratiche di antistrutture. Infine, si introduce il concetto di diagramma geometrico di gruppi e si calcolano esplicitamente i gruppi di ostruzione per un diagramma formato da 2-gruppi finiti.
Mon, 01 Jan 2001 00:00:00 GMThttp://hdl.handle.net/11380/4509712001-01-01T00:00:00ZUna rappresentazione delle trivarieta` orientabili mediante atlanti minimali di superficiehttp://hdl.handle.net/11380/451032Titolo: Una rappresentazione delle trivarieta` orientabili mediante atlanti minimali di superficie
Abstract: A representation theorem for orientable closed 3-manifolds is proved. Some applications about lens spaces, 3-manifolds of genus two, and connected sums are studied.
Tue, 01 Jan 1980 00:00:00 GMThttp://hdl.handle.net/11380/4510321980-01-01T00:00:00ZMobius transformations and surface groupshttp://hdl.handle.net/11380/451039Titolo: Mobius transformations and surface groups
Abstract: We describe a simple geometric construction of the fundamental group of the closed connected orientable surface of genus g (g greater or equal 2) presented in terms of 2g complex Mobius transformations as generators and of one relation among them. Our construction allows us to write the equation of any transformation of the above group. Finally, we give a recurrence formula to obtain all the vertices of the tessellation induced by the above group in the open unit disc endowed by the hyperbolic metric.
Tue, 01 Jan 1991 00:00:00 GMThttp://hdl.handle.net/11380/4510391991-01-01T00:00:00ZFinding nice crystallizations for handle free n-manifoldshttp://hdl.handle.net/11380/451017Titolo: Finding nice crystallizations for handle free n-manifolds
Abstract: The paper deals with combinatorial structures (pseudo-complexes, crystallizations) giving a direct link between the topology of triangulated manifolds and the theory of edge-colored multigraphs. We define the concept of regular crystallization of a manifold and prove that every non-trivial handle free closed n-manifold has a regular crystallization. Then we study some applications of regular crystallizations and give a counter-example to a conjecture of Y. Tsukui about strong frames of the 3-sphere.
Mon, 01 Jan 1990 00:00:00 GMThttp://hdl.handle.net/11380/4510171990-01-01T00:00:00ZOn the intersection forms of closed 4-manifoldshttp://hdl.handle.net/11380/451010Titolo: On the intersection forms of closed 4-manifolds
Abstract: Given a closed 4-manifold M, let M^* be the simply-connected 4-manifol obtained from M by killing the fundamental group. We study the relation between the intersection forms \lambda_M and \lambda_(M^*). Finally, some topological consequences and examples are described.
Wed, 01 Jan 1992 00:00:00 GMThttp://hdl.handle.net/11380/4510101992-01-01T00:00:00ZOn a certain surgery spectral sequencehttp://hdl.handle.net/11380/451041Titolo: On a certain surgery spectral sequence
Abstract: Given a morphism between twisted quadratic extensions of antistructures, we construct a spectral sequence which generalizes, in a natural way, the surgery spectral sequence introduced by Hambleton and Kharshiladze in Mat. sbornik 183 (1992). Our spectral sequence allows us to obtain some additional information about the Browder-Livesay invariants. Then we study the relations between the above-mentioned spectral sequences, and discuss some examples and applications.
Wed, 01 Jan 2003 00:00:00 GMThttp://hdl.handle.net/11380/4510412003-01-01T00:00:00ZSpecial classes of closed four-manifoldshttp://hdl.handle.net/11380/450979Titolo: Special classes of closed four-manifolds
Abstract: We present several results and state some open problems on the classification of topological and geometric structures of closed connected oriented (smooth) four-manifolds. In particular, we discuss many interesting classes of closed four-manifolds satisfying additional properties, that is, spin manifolds, manifolds with special homology (resp. homotopy), exact manifolds, geometric manifolds, and smooth manifolds. The results are obtained by using methods and techniques from algebraic and differential topology, and homological algebra.
Mon, 01 Jan 2001 00:00:00 GMThttp://hdl.handle.net/11380/4509792001-01-01T00:00:00ZTopologia delle varieta`: problemi e risultatihttp://hdl.handle.net/11380/450999Titolo: Topologia delle varieta`: problemi e risultati
Abstract: In questo articolo, di carattere generale, si espone una panoramica sui principali risultati classici e moderni, ottenuti da diversi autori, sul problema del riconoscimento delle varieta` topologiche e sul problema della classificazione omotopica e topologica delle varieta` TOP (PL, DIFF). Una serie di problemi aperti completano il testo dell'articolo.
Mon, 01 Jan 1996 00:00:00 GMThttp://hdl.handle.net/11380/4509991996-01-01T00:00:00Z