The uniqueness of the SDPS-set of the symplectic dual polar space ,

Abstract: SDPS-sets are very nice sets of points in dual polar spaces which themselves carry the structure of dual polar spaces. They were introduced in [B. De Bruyn, P. Vandecasteele, Valuations and hyperplanes of dual polar spaces, J. Combin. Theory Ser. A 112 (2005) 194–211] because they gave rise to new valuations and hyperplanes of dual polar spaces. In the present paper, we show that the symplectic dual polar space , , has up to isomorphisms a unique SDPS-set. [Copyright &y& Elsevier]