Abstract
Let X be a symplectic or odd orthogonal Grassmannian. We prove a Giambelli formula which expresses an arbitrary Schubert class in
$${{\mathrm{\mathrm {H}}}^*(X,{\mathbb Z})$$
H
∗
(
X
,
Z
)
as a polynomial in certain special Schubert classes. This polynomial, which we call a theta polynomial, is defined using raising operators, and we study its image in the ring of Billey–Haiman Schubert polynomials.