arXiv subjects

Sérgio Tadao Martins

Publications and source records attributed to Sérgio Tadao Martins.

4 recordsLinked to original sources

arXiv2019

The group Aut and Out of the fundamental group of a closed Sol 3-manifold

Let $E$ be the fundamental group of a closed Sol 3-manifold. We describe the groups $Aut(E)$ and $Out(E)$. We first consider the case where $E$ is the fundamental group of a torus bundle, and then the case where $E$ is the fundamental group of a closed Sol 3-manifold which is not a torus bundle. The groups are described in terms of some iterated semi-direct products of well known groups, where one exception is for $Out(E)$ for some $E$'s, in which case $Out(E)$ is described as an extension and a presentation is given.

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arXiv2016

The cohomology ring of the sapphires that admit the Sol geometry

Let $G$ be the fundamental group of a sapphire that admits the Sol geometry and is not a torus bundle. We determine a finite free resolution of $\mathbb{Z}$ over $\mathbb{Z}G$ and calculate a partial diagonal approximation for this resolution. We also compute the cohomology rings $H^*(G; A)$ for $A = \mathbb{Z}$ and $A = \mathbb{Z}/p$ for an odd prime $p$, and indicate how to compute the groups $H^*(G; A)$ and the multiplicative structure given by the cup product for any system of coefficients $A$.

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arXiv2016

The cohomology ring of certain families of periodic virtually cyclic groups

Let G be a virtually cyclic of the form (Z_a x Z_b) x Z or [Z_a x (Z b x Q_{2^i})] x Z. We compute the integral cohomology ring of G, and then obtain the periodicity of the Farell cohomology of these groups.

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arXiv2013

Diagonal approximation and the cohomology ring of torus fiber bundles

For a torus bundle (S^1 x S^1) -> E -> S^1$, we construct a finite free resolution Z over ZG, where G is the fundamental group of the total space E, and then we compute the cohomology groups H^*(G,Z) and H^*(G,Z_p) for a prime p. We also construct a partial diagonal approximation for the resolution, which allows us to compute the cup product in H^*(G,Z) and H^*(G,Z_p).

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