If (A,B) is a reachable linear system over commutative von Neumann regular ring R, finite collection of idempotent elements defined, constituting complete set invariants for the feedback equivalence. This allows us to construct explicitly canonical form. Relations are given among this idempotents and various other families invariants. For systems fixed sizes, equivalent classes put into 1-1 cor...

We study the first order theory of Bezout difference rings. In particular we show that rings of sequences very rarely have decidable theories as difference rings, or even decidable model completions. MSC: 03C60, 03B25, 12H10, 13L05

We study a simple variant of the von Neumann model of an expanding economy, in which multiple producers produce goods according to their production function. The players trade their goods at the market and then use the bundles acquired as inputs for the production in the next round. We show that a simple decentralized dynamic, where players update their bids proportionally to how useful the inv...

We prove that for all 1 ≤ p ≤ ∞, p 6= 2, the L spaces associated to two von Neumann algebras M, N are isometrically isomorphic if and only if M and N are Jordan *-isomorphic. This follows from a noncommutative L Banach-Stone theorem: a specific decomposition for surjective isometries of noncommutative L spaces.

X iv :m at h/ 04 09 13 9v 1 [ m at h. FA ] 8 S ep 2 00 4 A WEAK TYPE INEQUALITY FOR NON-COMMUTATIVE MARTINGALES AND APPLICATIONS NARCISSE RANDRIANANTOANINA Abstract. We prove a weak-type (1,1) inequality for square functions of noncommutative martingales that are simultaneously bounded in L and L. More precisely, the following non-commutative analogue of a classical result of Burkholder holds: ...

Let R be an associative ring with unity. An element a in R is said to be r-clean if a = e+r, where e is an idempotent and r is a regular (von Neumann) element in R. If every element of R is r-clean, then R is called an r-clean ring. In this paper, we prove that the concepts of clean ring and r-clean ring are equivalent for abelian rings. Further we prove that if 0 and 1 are the only idempotents...