Una generalizzazione di certe algebre che intervengono nella teoria dei sistemi
Usually, an abelian -group, even an archimedean -group, has a relatively large infinity of distinct -closures. Here, we find a reasonably large class with unique and perfectly describable -closure, the class of archimedean -groups with weak unit which are “-convex”. ( is the group of rationals.) Any is -convex and its unique -closure is the Alexandroff algebra of functions on defined from the clopen sets; this is sometimes .
A lattice-ordered ring is called an OIRI-ring if each of its order ideals is a ring ideal. Generalizing earlier work of Basly and Triki, OIRI-rings are characterized as those -rings such that is contained in an -ring with an identity element that is a strong order unit for some nil -ideal of . In particular, if denotes the set of nilpotent elements of the -ring , then is an OIRI-ring if and only if is contained in an -ring with an identity element that is a strong order unit....