Helena Reis

Dr. Helena Reis

Faculdade de Economia da Universidade do Porto, 4200-464 Porto, Portugal

Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 April 2006 in Nonlinear Analysis
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Journal Article
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HRHelena Reis
Helena Reis

27 August 2014 in Revista Matemática Iberoamericana
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Journal Article
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JRJulio C. Rebelo
Julio C. Rebelo
HRHelena Reis
Helena Reis
We introduce a method for estimating the size of the domain of definition of the solutions of a meromorphic vector field on a neighborhood of its pole divisor. The technique relies, in a certain sense, on obtaining a quantitative variant of some well-known results concerning the distance function between complex submanifolds in the presence of metrics with positive curvature. Several applications of these ideas are provided including a type of “confinement theorem” for the solutions of the differential equations associated to complete polynomial vector fields on \mathbb{C}^n as well as obstructions to realizing certain germs of vector fields as a singularity of a globally defined holomorphic vector field on a compact Kähler manifold. As a complement, a new approach to certain classical equations is proposed and detailed in the case of Halphen equations.

1 July 2013 in Compositio Mathematica
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JMJ.-F. Mattei
J.-F. Mattei
JRJulio Rebelo
Julio Rebelo
HRHelena Reis
Helena Reis
We show that generically a pseudogroup generated by holomorphic diffeomorphisms defined about $0\in \mathbb{C} $ is free in the sense of pseudogroups even if the class of conjugacy of the generators is fixed. This result has a number of consequences on the topology of leaves for a (singular) holomorphic foliation defined on a neighborhood of an invariant curve. In particular, in the classical and simplest case arising from local nilpotent foliations possessing a unique separatrix which is given by a cusp of the form $\{ {y}^{2} - {x}^{2n+ 1} = 0\} $ , our results allow us to settle the problem of showing that a generic foliation possesses only countably many non-simply connected leaves.

7 January 2014 in Journal of the London Mathematical Society
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Journal Article
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SPSusana Pinheiro
Susana Pinheiro
HRHelena Reis
Helena Reis

11 January 2016 in The Journal of Geometric Analysis
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Journal Article
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JRJulio Rebelo
Julio Rebelo
HRHelena Reis
Helena Reis

1 September 2015 in Bulletin of the Brazilian Mathematical Society, New Series
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Journal Article
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JRJulio Rebelo
Julio Rebelo
HRHelena Reis
Helena Reis