13,637 research outputs found
Formality of Donaldson submanifolds
We introduce the concept of s-formal minimal model as an extension of
formality. We prove that any orientable compact manifold M, of dimension 2n or
(2n-1), is formal if and only if M is (n-1)-formal. The formality and the hard
Lefschetz property are studied for the symplectic manifolds constructed by
Donaldson with asymptotically holomorphic techniques. This study permits us to
show an example of a Donaldson symplectic manifold of dimension eight which is
formal simply connected and does not satisfy the hard Lefschetz theorem.Comment: 24 pages, no figures, Latex2e; v3. statement of Lemma 2.7 correcte
An 8-dimensional non-formal simply connected symplectic manifold
A non-formal simply connected compact symplectic manifold of dimension 8 is
constructed.Comment: 8 pages, 1 figure; v2. exposition greatly improved; v3. final
version. To appear in Annals of Mathematic
On non-formal simply connected manifolds
We construct examples of non-formal simply connected and compact oriented
manifolds of any dimension bigger or equal to 7.Comment: 6 pages, Latex2
Characterization and evolution of the sediments of a Mediterranean coastal lagoon located next to a former mining area
Coastal lagoons are ecosystems that are relatively enclosed water bodies under the influence of both the terrestrial and themarine environment, being vulnerable to human impacts. Human activities, such asmining extraction, are significant anthropogenic coastal stressors that can negatively affect ecosystems and communities. In light of the above, the objective of this research is to examine the influence ofmetal mining activities on the composition of sediments of a Mediterranean coastal lagoon, named Mar Menor. This paper presents a comprehensive characterization for grain size, mineralogy, geochemistry and organic matter of sediments of this coastal lagoon, investigating their variation along space and time. Sedimentation dynamics are ruling clearly the grain size predominant in each area of the MarMenor coastal lagoon, determining the existence of entrainment, transport and sedimentation areas. Forminerals, elements and organic matter, sedimentation dynamics are also determining their distribution.The authors would like to thank Fundación Séneca for funding the project 12038/PI/09. In addition, they want to acknowledge the cooperation of J.M. Peñas, R. Baños, J. Saura, M. Saura and B. Villaescusa who helped us to improve this research and to Mr. and Mrs. Purves for their English grammar supervision
Formality and the Lefschetz property in symplectic and cosymplectic geometry
We review topological properties of K\"ahler and symplectic manifolds, and of
their odd-dimensional counterparts, coK\"ahler and cosymplectic manifolds. We
focus on formality, Lefschetz property and parity of Betti numbers, also
distinguishing the simply-connected case (in the K\"ahler/symplectic situation)
and the case (in the coK\"ahler/cosymplectic situation).Comment: 27 pages, no figures. Comments are welcome
Non-formal co-symplectic manifolds
We study the formality of the mapping torus of an orientation-preserving
diffeomorphism of a manifold. In particular, we give conditions under which a
mapping torus has a non-zero Massey product. As an application we prove that
there are non-formal compact co-symplectic manifolds of dimension and with
first Betti number if and only if and , or and
. Explicit examples for each one of these cases are given.Comment: Only minor changes with respect to version 1 (some terminology
clarified). 21 pages, no figures. To appear in Trans. Am. Math. So
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