Let M be a von Neumann algebra and ρ : M → M be a ∗-homomorphism. Then ρ is called a centrally extendable ∗-homomorphism (CEH) if there is a maximal abelian subalgebra (masa) M of the commutant M of M and a surjective ∗-homomorphism φ : M → M such that φ(Z) = ρ(Z) for all Z in the center of M. A ∗-ρderivation δ : M → M is called a centrally extendable ∗-ρ-derivation (CED) if there is a masa M o...

In this paper we show that over any field K of characteristic different from 2, the Maslov index gives rise to a 2-cocycle on the stable symplectic group with values in the Witt group. We also show that this cocycle admits a natural reduction to I2(K) and that the induced natural homomorphism from K2Sp(K)→ I2(K) is indeed the homomorphism given by the symplectic symbol {x, y} mapping to the Pfi...

The second central extension of the planar Galilei group has been alleged to have its origin in the spin variable. This idea is explored here by considering local Galilean covariant field theory for free fields of arbitrary spin. It is shown that such systems generally display only a trivial realization of the second central extension. While it is possible to realize any desired value of the ex...

A polynomial f(t) in an Ore extension K[t;S,D] over a division ring K is a Wedderburn polynomial if f(t) is monic and is the minimal polynomial of an algebraic subset of K. These polynomials have been studied in [LL5]. In this paper, we continue this study and give some applications to triangulation, diagonalization and eigenvalues of matrices over a division ring in the general setting of (S,D...

The prevalence of symptomatic syringomyelia in patients with chronic spinal cord injury (SCI) is around 4.5%. It is an important cause of treatable neurologic deterioration, although surgical shunting of the syrinx or arachnoid adhesiolysis of tethered elements have unpredictable results. Classically, syrinx extension causes progressive neuropathic pain, often with dissociated sensory loss due ...