Infinite sequence of fixed point free pseudo-Anosov homeomorphisms

We construct infinite sequences of pseudo-Anosov homeomorphisms without fixed points and leaving invariant a sequence of orientable measured foliations on the same topological surface and the same stratum of the space of abelian differentials. The existence of such sequences show that all pseudo-Anosov homeomorphisms fixing orientable measured foliations cannot be obtained by the Rauzy-Veech induction strategy

Volume entropy for surface groups via Bowen-Series like maps

We define a Bowen-Series like map for every geometric presentation of a co-compact surface group and we prove that the volume entropy of the presentation is the topological entropy of this particular (circle) map. Finally we find the minimal volume entropy among geometric presentations

Roots, symmetries and conjugacy of pseudo-Anosov mapping classes

An algorithm is proposed that solves two decision problems for pseudo-Anosov elements in the mapping class group of a surface with at least one marked fixed point. The first problem is the root problem: decide if the element is a power and in this case compute the roots. The second problem is the symmetry problem: decide if the element commutes with a finite order element and in this case compute this element. The structure theorem on which this algorithm is based provides also a new solution to the conjugacy problem

Identification of Strategic Industries: A Dynamic Perspective

Every once in a while, national governments face difficult decision problems regarding financial support of important domestic firms or even entire national national industries. Similar problems are often faced by regional or urban governments. Given these problems, it is important to get indications of the societal value of industries. In principle, input-output tables provide a lot of information in revealing the linkages between industries. On the basis of these tables, various measures of the value of industries have been derived. One of these measures is found by applying the 'hypothetical extraction method', originally proposed by Strassert (Jahrb.Nat.Stat., 1968) and refined and applied by, among others, Milana (MetrEc., 1985), Groenewold, Hagger & Madden (Reg.Stud., 1987) and Dietzenbacher & Van der Linden (J.Reg.Sci., 1997). This approach has two major drawbacks. First, it is a purely static approach, in which technological progress does not play a role at all. Second, it assumes that output and employment levels are purely demand-determined. In this paper, I propose a biregional supply-side input-output model with two factors of production (high-skilled and low-skilled labor) and interregional interindustry technology spillovers. Applying hypothetical extraction methods to this model yields an alternative framework for identifying important sectors in a dynamic sense.

Identification of strategic industries: a dynamic perspective

Reliable estimates of the economy-wide losses associated with closedown of an industry are generally hard to obtain. In the input-output literature, numerous measures of the social value of industries were proposed. These measures are mostly based on comparative statics results, whereas a dynamic perspective seems much more in demand. In this paper, "hypothetical extraction" methods are used in a new dynamic input-output model of economic growth. This model also stresses the importance of technological linkages between industries and of international trade performance. The potential power of the dynamic extraction methodology is illustrated by simulation results for a hypothetical economy.