  Let V be a nonsingular projective algebraic variety of dimension n. Suppose
there exists a very ample divisor D such that D^n=6 and dim H^0(V, O(D))=n+3.
Then, (V, D) defines a D_6-Galois embedding if and only if it is a Galois
closure variety of a smooth cubic in P^{n+1} with respect to a suitable
projection center such that the pull back of hyperplane of P^n is linearly
equivalent to D.
