Classification of regular embeddings of hypercubes of odd dimension

By a regular embedding of a graph into a closed surface we mean a 2-cell embedding with the automorphism group acting regularly on flags. Recently, Kwon and Nedela [Non-existence of nonorientable regular embeddings of n-dimensional cubes, Discrete Math., to appear] showed that no regular embeddings of the n-dimensional cubes Q"n into nonorientable surfaces exist for any positive integer n>2. In 1997, Nedela and Skoviera [Regular maps from voltage assignments and exponent groups, European J. Combin. 18 (1997) 807-823] presented a construction giving for each solution of the congruence e^2=1(modn) a regular embedding M"e of the hypercube Q"n into an orientable surface. It was conjectured that all regular embeddings of Q"n into orientable surfaces can be constructed in this way. This paper gives a classification of regular embeddings of hypercubes Q"n into orientable surfaces for n odd, proving affirmatively the conjecture of Nedela and Skoviera for every odd n.