REFINEMENT RINGS, EXCHANGE PROPERTY AND COMPARABILITY

Elements in Exchange Rings with Related Comparability

We show that if R is an exchange ring, then the following are equivalent: (1) R satisfies related comparability. (2) Given a,b,d ∈ R with aR+bR = dR, there exists a related unit w ∈ R such that a+bt = dw. (3) Given a,b ∈ R with aR = bR, there exists a related unit w ∈ R such that a= bw. Moreover, we investigate the dual problems for rings which are quasi-injective as right modules.

Refinement Monoids with Weak Comparability and Applications to Regular Rings and C∗-algebras

We prove a cancellation theorem for simple refinement monoids satisfying the weak comparability condition, first introduced by K.C. O’Meara in the context of von Neumann regular rings. This result is then applied to von Neumann regular rings and C∗-algebras of real rank zero via the monoid of isomorphism classes of finitely generated projective modules. Introduction Let M be an (abelian) monoid...

Diagonal Matrix Reduction over Refinement Rings

  Abstract: A ring R is called a refinement ring if the monoid of finitely generated projective R- modules is refinement.  Let R be a commutative refinement ring and M, N, be two finitely generated projective R-nodules, then M~N  if and only if Mm ~Nm for all maximal ideal m of  R. A rectangular matrix A over R admits diagonal reduction if there exit invertible matrices p and Q such that PAQ is...

Countable Exchange and Full Exchange Rings

We show that a Dedekind-finite, semi-π-regular ring with a “nice” topology is an א0-exchange ring, and the same holds true for a strongly clean ring with a “nice” topology. We generalize the argument to show that a Dedekind-finite, semi-regular ring with a “nice” topology is a full exchange ring. Putting these results in the language of modules, we show that a cohopfian module with finite excha...

Exchange rings, exchange equations, and lifting properties