Farrell cohomology of GL(n,Z)

The Tate-Farrell cohomology of GL(n,Z) with coefficients inZ/p is computed forp an odd prime andp−1 ≦n ≦ 2p−3. Its size depends on the Galois structure of the class group of the cyclotomic fieldQ(p√1) and is shown to be quite large in general. Research partially supported by NSF Grant No. DMS-8701758.     

Effective permeability of the boundary of a domain

Let u be a solution of the Laplace equation in a boilnded domain Ω in R ⁿ whose boundary consists of two disjoint surfaces λ₀ and λ₁. On λ₁ u satisfies a Dirichlet boundary condition, whereas on Λ₀ u satisfies the impermeability condition ?u/?n = 0 ever3 where except on m, small “holes” λ, separated from one another by distance of older of magnitude ε. and u= O on the holes. In this paper wr study the effective periwabilitv of the surface λ₀as ε→0.     

A planning model for crisis management in the tourism sector

The article proposes an analytical planning framework for managing crisis situations in the tourism industry. It applies the principle of acting in successive phases by which each stage aims to reduce the residual negative effects remaining after implementing the preceding one. The first phase relates to pre-crisis policy measures designed to reduce the overall sensitivity of the industry to crisis situations, the second phase deals with response policies to be implemented when conditions of crisis-certainty exist, and the third phase considers various specific short-term supplementary measures.The optimization process employs portfolio theory and linear programming models. It can be used by governmental agencies in charge of long-range countrywide or regional planning as an auxiliary tool for policy decesions.