Let U be an n-dimensional
vector space over an algebraically closed field F of characteristic zero, and let ∨rU
denote the r-th symmetric product space of U. Let T be a linear transformation on
∨rU which sends nonzero decomposable elements to nonzero decomposable elements.
We prove the following:
If n = r + 1 then T is induced by a nonsingular transformation on T.
If 2 < n < r + 1 then either T is induced by a nonsingular transformation
on U or T(∨rU) =∨rW for some two dimensional subspace W of U.
The result for n > r+1 was recently obtained by L. J. Cummings.