Published online by Cambridge University Press: 20 November 2018
Virasoro-toroidal algebras, ${{\tilde{J}}_{[n]}}$ , are semi-direct products of toroidal algebras
${{J}_{[n]}}$ and the Virasoro algebra. The toroidal algebras are, in turn, multi-loop versions of affine Kac-Moody algebras. Let
$\Gamma $ be an extension of a simply laced lattice
$\dot{Q}$ by a hyperbolic lattice of rank two. There is a Fock space
$V\left( \Gamma\right)$ corresponding to
$\Gamma $ with a decomposition as a complex vector space:
$V\left( \Gamma\right)=\coprod{_{m\in z}K\left( m \right)}$ . Fabbri and Moody have shown that when
$m\ne 0,\,K\left( m \right)$ is an irreducible representation of
${{\tilde{J}}_{[2]}}$ . In this paper we produce a filtration of
${{\tilde{J}}_{[2]}}$ -submodules of
$K\left( 0 \right)$ . When
$L$ is an arbitrary geometric lattice and
$n$ is a positive integer, we construct a Virasoro-Heisenberg algebra
$\tilde{H}\left( L,n \right)$ . Let
$Q$ be an extension of
$\dot{Q}$ by a degenerate rank one lattice. We determine the components of
$V\left( \Gamma\right)$ that are irreducible
$\tilde{H}\left( Q,1 \right)$ -modules and we show that the reducible components have a filtration of
$\tilde{H}\left( Q,1 \right)$ -submodules with completely reducible quotients. Analogous results are obtained for
$\tilde{H}\left( \dot{Q},2 \right)$ . These results complement and extend results of Fabbri and Moody.