Advanced Operator Algebra Research

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• MURAT ALTUNBULAK

Let M be a compact Stein surface with boundary.We show that M admits infinitely many pairwise nonequivalent positive allowable Lefschetz fibrations over D 2 with bounded fibers.

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• ÖZGÜR MARTİN

For every integer g ≥ 2 there exist infinitely many pairwise nonhomeomorphic smooth 4-manifolds admitting genus-g Lefschetz fibration over S2 but not carrying any complex structure. This extends a recent result of Ozbagci and Stipsicz.

We promote the open-closed string map, originally formulated by Seiberg Witten, to a solution generating prescription in generalized supergravity. The approach hinges on a knowledge of an antisymmetric bivector $\mathrm{\ensuremath{\Theta}}$, built from antisymmetric products of Killing vectors, which is specified by…

• ÖZGÜR KELEKÇİ

Let M be a smooth 4-manifold which admits a Lefschetz fibration over D 2 or S 2 .We develop an algorithm to compute the signature of M using the global monodromy of this fibration.As a corollary we prove that there is no hyperelliptic Lefschetz fibration over S 2 with only reducible singular fibers.

We describe explicit open books on arbitrary plumbings of oriented circle bundles over closed oriented surfaces. We show that, for a non-positive plumbing, the open book we construct is horizontal and the corresponding compatible contact structure is also horizontal and Stein fillable. In particular, on some Seifert f…

Continuing a line of research initiated by Larsen, Liu and Wang [12], Martin and Yap [13], Gürkanli [15], and influenced by Reiter′s presentation of Beurling and Segal algebras in Reiter [2,10] this paper presents the study of a family of Banach ideals of Beurling algebras , G a locally compact Abelian group. These sp…

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• UĞUR TIRNAKLI

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• SERKAN SÜTLÜ

Abstract Motivated by possible scalar-leptoquark explanations of the recently reportedB-decay anomalies, we investigate whether the required leptoquarks can be accommodated within models based on noncommutative geometry (NCG). The models considered have the gauge structure of Pati-Salam models, SU(4) × SU(2)L× SU(2)R,…

• UFUK AYDEMİR

In this paper we study finite group extensions represented by special cohomology classes. As an application, we obtain some restrictions on finite groups which can act freely on a product of spheres or on a product of real projective spaces. In particular, we prove that if $(Z/p)^r$ acts freely on $(S^1)^k$, then $r \…