Peripheral acyclicity in 3-manifolds
نویسندگان
چکیده
منابع مشابه
Acyclicity in Three-manifolds
An acyclic compactum in an orientable, open 3-manifold has arbitrarily close, polyhedral neighborhoods whose components are compact 3-manifolds with a special structure. Frequently, these 3-manifolds have free fundamental groups. These observations and some results from combinatorial group theory are exploited to deduce facts about the homomorphism of fundamental groups induced by an acyclic ma...
متن کاملFlats in 3-manifolds
— We prove that if a closed aspherical Riemannian 3-manifold M contains a 2-flat, then there exists a free abelian subgroup of rank two in π1(M). Under some restrictions on the topology of M we prove the existence of an immersed incompressible flat torus in M . This generalizes results which were previously known for manifolds of nonpositive curvature. RÉSUMÉ. — Nous prouvons que si une variété...
متن کاملContaminations in 3-Manifolds
We propose in this paper a method for studying contact structures in 3manifolds by means of branched surfaces. We explain what it means for a contact structure to be carried by a branched surface embedded in a 3-manifold. To make the transition from contact structures to branched surfaces, we first define auxiliary objects called σ-confoliations and pure contaminations, both generalizing contac...
متن کاملAcyclicity and reduction
The literature provides dichotomies involving homomorphisms (like the G0 dichotomy) or reductions (like the characterization of sets potentially in a Wadge class of Borel sets, which holds on a subset of a product). However, part of the motivation behind the latter result was to get reductions on the whole product, like in the classical notion of Borel reducibility considered in the study of an...
متن کاملOn the Relationship of Joint Acyclicity and Super-Weak Acyclicity
Rules that allow existential quantifiers in the head (conclusion) have been studied extensively in knowledge representation, databases, and logic programming (in the related form of logic programs with function symbols). In general, it is not decidable if a set of such rules admits a finite model, but a number of sufficient conditions have been proposed to detect situations where this is the ca...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Journal of the Australian Mathematical Society. Series A. Pure Mathematics and Statistics
سال: 1987
ISSN: 0263-6115
DOI: 10.1017/s1446788700028597