In their study of characters of minimal affinizations of representations of orthogonal
and symplectic Lie algebras, Chari and Greenstein conjectured that certain
Jacobi–Trudi determinants satisfy an alternating sum formula. In this note, we prove
their conjecture and slightly more. The proof relies on some symmetries of the ring of
symmetric functions discovered by Koike and Terada. Using results of Hernandez,
Mukhin and Young, and Naoi, this implies that the characters of minimal
affinizations in types B, C, and D are given by a Jacobi–Trudi determinant.