Type IIB orientifolds with discrete torsion

We consider compact four-dimensional ${\bf Z_N}\times {\bf Z_M}$ type IIB orientifolds, for certain values of $N$ and $M$. We allow the additional feature of discrete torsion and discuss the modification of the consistency conditions arising from tadpole cancellation. We point out the differences between the cases with and without discrete torsion.Comment: 4 pages LaTeX. Write-up of talk at DPF2000, Columbus, OH, August 10, 2000. References adde

Quantum symmetries and exceptional collections

We study the interplay between discrete quantum symmetries at certain points in the moduli space of Calabi-Yau compactifications, and the associated identities that the geometric realization of D-brane monodromies must satisfy. We show that in a wide class of examples, both local and compact, the monodromy identities in question always follow from a single mathematical statement. One of the simplest examples is the Z_5 symmetry at the Gepner point of the quintic, and the associated D-brane monodromy identity

A Two-loop Test of Buscher's T-duality I

We study the two loop quantum equivalence of sigma models related by Buscher's T-duality transformation. The computation of the two loop perturbative free energy density is performed in the case of a certain deformation of the SU(2) principal sigma model, and its T-dual, using dimensional regularization and the geometric sigma model perturbation theory. We obtain agreement between the free energy density expressions of the two models.Comment: 28 pp, Latex, references adde

Scaling Limits for Internal Aggregation Models with Multiple Sources

We study the scaling limits of three different aggregation models on Z^d: internal DLA, in which particles perform random walks until reaching an unoccupied site; the rotor-router model, in which particles perform deterministic analogues of random walks; and the divisible sandpile, in which each site distributes its excess mass equally among its neighbors. As the lattice spacing tends to zero, all three models are found to have the same scaling limit, which we describe as the solution to a certain PDE free boundary problem in R^d. In particular, internal DLA has a deterministic scaling limit. We find that the scaling limits are quadrature domains, which have arisen independently in many fields such as potential theory and fluid dynamics. Our results apply both to the case of multiple point sources and to the Diaconis-Fulton smash sum of domains.Comment: 74 pages, 4 figures, to appear in J. d'Analyse Math. Main changes in v2: added "least action principle" (Lemma 3.2); small corrections in section 4, and corrected the proof of Lemma 5.3 (Lemma 5.4 in the new version); expanded section 6.

Gauge-invariant gluon mass, infrared Abelian dominance and stability of magnetic vacuum

We give an argument for deriving analytically the infrared ``Abelian'' dominance in a gauge invariant way for the Wilson loop average in SU(2) Yang--Mills theory. In other words, we propose a possible mechanism for realizing the dynamical Abelian projection in the SU(2) gauge-invariant manner without breaking color symmetry. This supports validity of the dual superconductivity picture for quark confinement. We also discuss the stability of the vacuum with magnetic condensation as a by-product of this result.Comment: 25 pages, 3 figures (4 eps files); version accepted for publication in Phys.Rev.D; One paragraph is added at each end of sections 3,4 and 5 for comparing the analytical result with the lattice results of my group based on the new formulation, together with the results in the conventional MAG if available. footnote 4 is added, and a reference is added. A number of sentences and phrases are improve

Approximate Deadline-Scheduling with Precedence Constraints

We consider the classic problem of scheduling a set of n jobs non-preemptively on a single machine. Each job j has non-negative processing time, weight, and deadline, and a feasible schedule needs to be consistent with chain-like precedence constraints. The goal is to compute a feasible schedule that minimizes the sum of penalties of late jobs. Lenstra and Rinnoy Kan [Annals of Disc. Math., 1977] in their seminal work introduced this problem and showed that it is strongly NP-hard, even when all processing times and weights are 1. We study the approximability of the problem and our main result is an O(log k)-approximation algorithm for instances with k distinct job deadlines

Transformation of tax instruments to stimulate investment processes

The article examines the practice of applying various tax instruments to stimulate largescale investment processes. The purpose of the study is to analyse tax instruments to stimulate these investment processes from the point of view of their impact on the final outcome. The authors decided tasks: to consider the taxes benefits and preferences as tools for stimulating large-scale investment processes; to identify opportunities for creating the most favorable tax climate for these investment projects; to assess the possibility of expanding such a tax administration tool as tax monitoring, subject to the inclusion of organisations implementing large investment projects as taxpayers. The authors’ recommendations and conclusions can be used in the development of conceptual provisions of tax policy both at the regional and state level in the field of tax regulation of investment processes

TAX CHALLENGES OF THE DIGITAL ECONOMY

The issues of changing the tax system of the Russian Federation, the system of tax control under the influence of digital technologies have been examined. Electronic government services in the field of taxation, as well as the prospects and directions for the further development and expansion of electronic services used for taxpayers and tax authorities have been considered. The problems of taxation of operations with cryptocurrencies and their tax regulation have been touched upon. Conclusions have been formulated to improve the efficiency of taxation and tax control in the transition to a digital economy

Role of tax security in organization economic security system

The article studies problematic issues of tax security as a part of the organization’s economic security. Successful operation of a company depends on tax compliance, correct definition of the tax function, and timely identification of tax risks. The purpose of the research is to justify the role of tax security as one of the key parts of the organization’s economic security. The approaches to minimizing the tax risks of companies have been analyzed. The arbitration practice, letters from the Federal Tax Service of Russia, and various interactive services that allow taxpayers to conduct economic analysis have been reviewed. The main problems that may arise for organizations in building the tax security system have been highlighted and the possible ways of solving it defined. The article concludes that it is necessary to approve the organization’s tax risk of management regulations and comprehensive diagnostics of the internal tax control system for the taxpayers who do not apply tax monitoring. The results obtained can be used in the formation of regulations on the organization’s tax planning, improving the provisions of the orders of the Federal Tax Service of Russia on the requirements for organization of internal tax control system for the taxpayers who do not apply tax monitoring

Prospects for the application of unified tax payment in the digital economy

The unified tax payment is to simplify the payment of taxes, reduce the time for filling out payment documents and reduce the number of mistakes in them. The purpose of the paper is to analyze the use of the unified tax payment from the perspective of its impact on tax administration and taxpayers’ activities.In this article, the authors set the following tasks: to determine the procedure for paying the unified tax payment; to assess the possibility of expanding the practice of its application and identify possible problems.The data on the voluntary remittances of the unified tax payment by physical persons during the period from 2019 to 2022 is presented. A critical analysis of the draft laws No. 46702-8 «On Amendments to Part One and Part Two of the Tax Code of the Russian Federation (in terms of improving the procedure for paying taxes) and No. 20281-8 «On conducting an experiment to establish a special tax regime «Automated simplified taxation system» is carried out. The paper highlights the main problems which companies may face if the institution of the «unified tax payment» is applied on a mandatory basis and identifies the possible ways to solve them. The authors’ recommendations and conclusions can be used in the development of conceptual provisions of tax policy