THE MORDELL-WEIL GROUPS OF UNIRATIONAL QUASI-ELLIPTIC SURFACES IN CHARACTERISTIC-2

We continue to study the Mordell-Weil groups of unirational quasi-elliptic surfaces. We classify them in the case of rational quasi-elliptic surfaces in characteristic 2 and show how to construct them from the projective plane. In the classification, a key role is played by a theorem which guarantees that the relevant properties of unirational quasi-elliptic surfaces are determined explicitly by the equations of the surfaces as affine hypersurface.