Frobenius $n$-homomorphisms, transfers and branched coverings
  The main purpose is to characterise continuous maps that are $n$-branched coverings in terms of induced maps on the rings of functions. The special properties of Frobenius $n$-homomorphisms between two function spaces that correspond to $n$-branched coverings are determined completely. Several equivalent definitions of a Frobenius $n$-homomorphism are compared and some of their properties are proved. An axiomatic treatment of $n$-transfers is given in general and properties of $n$-branched coverings are studied and compared with those of regular coverings. 
V.M.Buchstaber, E.G.Rees