  Generalizing Tate's results for tori, we give closed formulas for the abelian
Galois cohomology groups H^1_{ab}(F,G) and H^2_{ab}(F,G) of a connected
reductive group G over a global field F, and obtain formulas, suitable for
computer calculatios, for the first nonabelian Galois cohomology set H^1(F,G)
of G and for the second Galois cohomology group H^2(F,T) of an F-torus T.
