文摘
Let n2, let be fields such that is a quadratic Galois-extension of and let θ denote the unique nontrivial element in . Suppose the symplectic dual polar space is fully and isometrically embedded into the Hermitian dual polar space . We prove that the projective embedding of induced by the Grassmann-embedding of is isomorphic to the Grassmann-embedding of . We also prove that if n is even, then the set of points of at distance at most from is a hyperplane of which arises from the Grassmann-embedding of .