279 research outputs found

    The Killing tensors on an nn -dimensional manifold with SL(n,R)SL(n, R)-structure

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    In this paper we solve the problem of finding integrals of equations determining the Killing tensors on an nn -dimensional differentiable manifold MM endowed with an equiaffine SL(n,R) SL(n, R) -structure and discuss possible applications of obtained results in Riemannian geometry

    The Seven Classes of the Einstein Equations

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    In current paper we refer to the geometrical classification of the Einstein equations which has been developed by one of the authors of this paper. This classification was based on the classical theory for decomposition of the tensor product of representations into irreducible components, which is studied in the elementary representation theory for orthogonal groups. We return to this result for more detailed investigation of classes of the Einstein equations.Comment: 9page

    From the Ricci flow evolution equation to vanishing theorems for Ricci solitons

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    In the paper, we study evolution equations of the scalar and Ricci curvatures under the Hamilton's Ricci flow on a closed manifold and on a complete noncompact manifold. In particular, we study conditions when the Ricci flow is trivial and the Ricci soliton is Ricci flat or Einstein.Comment: 10 page

    Geometry in the large of the kernel of Lichnerowicz Laplacians and its applications

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    There are very few general theorems on the kernel of the well-known Lichnerowicz Laplacian. In the present article we consider the geometry of the kernel of this operator restricted to covariant (not necessarily symmetric or skew-symmetric) tensors. Our approach is based on the analytical method, due to Bochner, of proving vanishing theorems for the null space of Laplace operator. In particular, we pay special attention to the kernel of the Lichnerowicz Laplacian on Riemannian symmetric spaces of compact and noncompact types. In conclusion, we give some applications to the theories of infinitesimal Einstein deformations and the stability of Einstein manifolds.Comment: 19 page

    A Method with Feedback for Aggregation of Group Incomplete Pair-Wise Comparisons

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    A method for aggregation of expert estimates in small groups is proposed. The method is based on combinatorial approach to decomposition of pair-wise comparison matrices and to processing of expert data. It also uses the basic principles of Analytic Hierarchy/Network Process approaches, such as building of criteria hierarchy to decompose and describe the problem, and evaluation of objects by means of pair-wise comparisons. It allows to derive priorities based on group incomplete pair-wise comparisons and to organize feedback with experts in order to achieve sufficient agreement of their estimates. Double entropy inter-rater index is suggested for usage as agreement measure. Every expert is given an opportunity to use the scale, in which the degree of detail (number of points/grades) most adequately reflects this expert's competence in the issue under consideration, for every single pair comparison. The method takes all conceptual levels of individual expert competence (subject domain, specific problem, individual pair-wise comparison matrix, separate pair-wise comparison) into consideration. The method is intended to be used in the process of strategic planning in weakly-structured subject domains.Comment: 13 pages, 6 figure

    A remark on the Laplacian operator which acts on symmetric tensors

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    More than forty years ago J. H. Samson has defined the Laplacian Ξ”sym\Delta_{sym} acting on the space of symmetric covariant pp-tensors on an nn-dimensional Riemannian manifold (M,g)(M, g). This operator is an analogue of the well known Hodge-de Rham Laplacian Ξ”\Delta which acts on the space of exterior differential pp-forms (1≀p≀n1 \le p \le n) on (M,g)(M, g). In the present paper we will prove that for n>p=1n > p = 1 the operator Ξ”sym\Delta_{sym} is the Yano rough Laplacian and show its spectrum properties on a compact Riemannian manifold.Comment: Riemannian manifold, second order elliptic differential operator on 1-forms, eigenvalues and eigenform

    Conformal Killing L2βˆ’L^{2}-forms on complete Riemannian manifolds with nonpositive curvature operator

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    We give a classification for connected complete locally irreducible Riemannian manifolds with nonpositive curvature operator, which admit a nonzero closed or co-closed conformal Killing L2βˆ’L^{2}-form. Moreover, we prove vanishing theorems for closed and co-closed conformal Killing L2βˆ’L^{2}-forms on some complete Riemannian manifolds

    Usage of Decision Support Systems for Conflicts Modelling during Information Operations Recognition

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    Application of decision support systems for conflict modeling in information operations recognition is presented. An information operation is considered as a complex weakly structured system. The model of conflict between two subjects is proposed based on the second-order rank reflexive model. The method is described for construction of the design pattern for knowledge bases of decision support systems. In the talk, the methodology is proposed for using of decision support systems for modeling of conflicts in information operations recognition based on the use of expert knowledge and content monitoring.Comment: 8 pages, 1 figur

    From harmonic mappings to Ricci solitons

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    The paper is devoted to the study of the global geometries of harmonic mappings and infinitesimal harmonic transformations and presents their applications to the theory of Ricci solitons

    Comparing Efficiency of Expert Data Aggregation Methods

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    Expert estimation of objects takes place when there are no benchmark values of object weights, but these weights still have to be defined. That is why it is problematic to define the efficiency of expert estimation methods. We propose to define efficiency of such methods based on stability of their results under perturbations of input data. We compare two modifications of combinatorial method of expert data aggregation (spanning tree enumeration). Using the example of these two methods, we illustrate two approaches to efficiency evaluation. The first approach is based on usage of real data, obtained through estimation of a set of model objects by a group of experts. The second approach is based on simulation of the whole expert examination cycle (including expert estimates). During evaluation of efficiency of the two listed modifications of combinatorial expert data aggregation method the simulation-based approach proved more robust and credible. Our experimental study confirms that if weights of spanning trees are taken into consideration, the results of combinatorial data aggregation method become more stable. So, weighted spanning tree enumeration method has an advantage over non-weighted method (and, consequently, over logarithmic least squares and row geometric mean methods).Comment: 16 pages, 6 figures, 5 table
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