3,283 research outputs found

    Pseudo-Anosov flows in toroidal manifolds

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    We first prove rigidity results for pseudo-Anosov flows in prototypes of toroidal 3-manifolds: we show that a pseudo-Anosov flow in a Seifert fibered manifold is up to finite covers topologically equivalent to a geodesic flow and we show that a pseudo-Anosov flow in a solv manifold is topologically equivalent to a suspension Anosov flow. Then we study the interaction of a general pseudo-Anosov flow with possible Seifert fibered pieces in the torus decomposition: if the fiber is associated with a periodic orbit of the flow, we show that there is a standard and very simple form for the flow in the piece using Birkhoff annuli. This form is strongly connected with the topology of the Seifert piece. We also construct a large new class of examples in many graph manifolds, which is extremely general and flexible. We construct other new classes of examples, some of which are generalized pseudo-Anosov flows which have one prong singularities and which show that the above results in Seifert fibered and solvable manifolds do not apply to one prong pseudo-Anosov flows. Finally we also analyse immersed and embedded incompressible tori in optimal position with respect to a pseudo-Anosov flow.Comment: 44 pages, 4 figures. Version 2. New section 9: questions and comments. Overall revision, some simplified proofs, more explanation

    Quasi-Fuchsian AdS representations are Anosov

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    In a recent paper, Q. M\'erigot proved that representations in SO(2,n) of uniform lattices of SO(1,n) which are Anosov in the sense of Labourie are quasi-Fuchsian, i.e. are faithfull, discrete, and preserve an acausal subset in the boundary of anti-de Sitter space. In the present paper, we prove the reverse implication. It also includes: -- A construction of Dirichlet domains in the context of anti-de Sitter geometry, -- A proof that spatially compact globally hyperbolic anti-de Sitter spacetimes with acausal limit set admit locally CAT(-1) Cauchy hypersurfaces

    Does Airport Regulation Benefit Consumers?

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    Airport regulation is aimed to impose price caps or other schemes on services supplied by airports to airlines that use them. However, it is not clear that regulation benefits the final consumers, the passengers. In the context of a very simple model, this paper finds out that this doesn’t always happen, and that passengers may be worse off with price capping than in an unregulated equilibrium. Besides, the paper provides an insight of the results of other regulation approaches (other than price caps) that have been suggested for airports.

    Low cost carriers, secondary airports and State aid: an economic assessment of the Charleroi affair

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    In this paper a vertical differentiation model is built in order to analyse the effects of subsidies to secondary airports, or of lower prices set by them, on the competition between LCC’s and FSC’s. The Ryanair/ Charleroi agreement is used as an example and as a basis for the model. The main findings are that subsidisation (or lower airport charges) benefits consumers and negatively affects incumbent airlines. However, they may be more affected by competition than by the subsidy. An empirical analysis provides a few insights on LCC’s price strategies, namely that they retain rents resulting from lower aeronautical fees on dominated airports, and that their price strategy does not change with the presence of other LCC’s.Low cost carriers, airports, airline competition, State aid.