Poincaré-Verdier Duality

The cohomological dimension for rings and topological spaces is introduced in the first section. The second section contains the main results of Verdier duality, including the properties of the dualizing sheaf ω _X . The very general results of this section are specialized in the next section, yielding the usual Poincaré duality and Alexander duality. Here the dual sheaf complex is also introduced, and its compatibility with direct and inverse images is clearly stated. The last section contains a number of basic vanishing results for the cohomology of Stein spaces with local system coefficients.