Canonical coverings of Enriques surfaces in characteristic 2

抄録

Let \bar{𝑌} be a normal surface that is the canonical 𝜇₂- or 𝛼₂-covering of a classical or supersingular Enriques surface in characteristic 2. We determine all possible configurations of singularities on \bar{𝑌}, and for each configuration we describe which type of Enriques surfaces (classical or supersingular) appear as quotients of \bar{𝑌}.