We first present a generalization of the Robertson-Heisenberg uncertainty principle. This applies to mixed states and contains covariance term. For faithful states, we characterize when inequality is an equality. next principle version for real-valued observables. Sharp versions conjugates observables are considered. The theory illustrated with examples dichotomic close discussion coarse graini...

Abstract. Given a real hyperplane arrangement A, the complement M(A) of the complexification of A admits an action of the group Z2 by complex conjugation. We define the equivariant Orlik-Solomon algebra of A to be the Z2-equivariant cohomology ring of M(A) with coefficients in the field F2. We give a combinatorial presentation of this ring, and interpret it as a deformation of the ordinary Orli...

Let S be a semigroup. In certain cases we give some characterizations of extreme amenability of S and we show that in these cases extreme left amenability and extreme right amenability of S are equivalent. Also when S is a compact topological semigroup, we characterize extremely left amenable subalgebras of C(S), where C(S) is the space of all continuous bounded real valued functions on S

When D is an integral domain with field of fractions K, the ring Int(D) = {f(x) ∈ K[x] | f(D) ⊆ D} of integer-valued polynomials over D has been extensively studied. We will extend the integer-valued polynomial construction to certain noncommutative rings. Specifically, let i, j, and k be the standard quaternion units satisfying the relations i = j = −1 and ij = k = −ji, and define ZQ := {a+bi+...