Unbroken SU(3) symmetry and the relation of interacting-boson-model parameters with the shell model.

The predictions of the exact SU(3) symmetry limit of the interacting boson model are reviewed for the Dy--Pt region. Evidence of a functional relationship of the coefficient ..cap alpha.. of the L(L+1) term in the expression for energy in the SU(3) limit with the product N/sub p/N/sub n/ is presented, with a similar relation for B(E2,2/sub 1//sup +/-0/sub 1//sup +/). In contrast, the absence of a simple direct relationship of the coefficient ..beta.. ( = K) of C(lambda,..mu..) or of the SU(3) symmetry breaking term K''/K with N/sub p/,N/sub n/ is illustrated. The possible reasons are discussed.