  Boolean ultrapowers extend the classical ultrapower construction to work with
ultrafilters on any complete Boolean algebra, rather than only on a power set
algebra. When they are well-founded, the associated Boolean ultrapower
embeddings exhibit a large cardinal nature, and the Boolean ultrapower
construction thereby unifies two central themes of set theory---forcing and
large cardinals---by revealing them to be two facets of a single underlying
construction, the Boolean ultrapower.
