Generalizing homogeneous
spectra for rings graded by natural numbers, we introduce multihomogeneous spectra
for rings graded by abelian groups. Such homogeneous spectra have the
same completeness properties as their classical counterparts, but are possibly
nonseparated. We relate them to ample families of invertible sheaves and simplicial
toric varieties. As an application, we generalize Grothendieck’s Algebraization
Theorem and show that formal schemes with certain ample families are
algebraizable.