Let $W = \mathbb {C}[t,t^{-1}]\partial _t$ be the Witt algebra of algebraic vector fields on $\mathbb {C}^\times$ and let $V\!ir$ Virasoro , unique nontrivial central extension $W$ . In this paper, we study Poisson ideal structure symmetric algebras as well several related Lie algebras. We classify prime ideals primitive $\operatorname {S}(V\!ir)$ {S}(W)$ particular, show that only functions in...