Symplectic Shifted Tableaux and Deformations of Weyl's Denominator Formula for <Emphasis Type="Italic">sp</Emphasis>(2<Emphasis Type="Italic">n</Emphasis>)

A determinantal expansion due to Okada is used to derive both a deformation of Weyl’s denominator formula for the Lie algebra sp(2n) of the symplectic group and a further generalisation involving a product of the deformed denominator with a deformation of flagged characters of sp(2n). In each case the relevant expansion is expressed in terms of certain shifted sp(2n)-standard tableaux. It is then re-expressed, first in terms of monotone patterns and then in terms of alternating sign matrices.