Let E be a Banach lattice. Its ideal center Z (E) is embedded naturally in the ideal center Z (E ) of its dual. The embedding may be extended to a contractive algebra and lattice homomorphism of Z (E) into Z (E ). We show that the extension is onto Z (E ) if and only if E has a topologically full center. (That is, for each x ∈ E, the closure of Z (E)x is the closed ideal generated by x.) The result can be generalized to the ideal center of the order dual of an Archimedean Riesz space and in a modified form to the orthomorphisms on the order dual of an Archimedean Riesz space.
Mathematics Subject Classification (2000)Primary 47B38 · 47B60 · 46B42; Secondary 46H25 · 47L10