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## Ещё раз об определении предмета математики и о периодизации её истории

Аbout approaches to the definition of a subject of mathematics and about a periodization of its history

With regard to social disciplines, a question continually arises: are mathematical methods fit for analyzing historical and social processes? Obviously, we should not absolutize differences between fields of knowledge, but the division of sciences into two opposite types, made by W. Windelband and H. Rickert, is still valid. As is known, they singled out sciences involving *nomo-thetic methods, *i.e., looking for general laws and generalizing phenomena, and those applying *idiographic methods, *i.e., describing individual and unique events and objects. Rickert attributed history to the second type. In his opinion, history always aims at picturing an isolated and more or less wide course of development in all its uniqueness and individuality

The significance of the education in the field of philosophy of mathematics as the part of both philosohpy and mathematics at the universities is the subject of the article.

*There is no doubt that periodization is a rather effective method of data ordering and analysis, but it deals with exceptionally complex types of processual and temporal phenomena and thus it simplifies historical reality. Many scholars emphasize the great importance of periodization for the study of history. In fact, any periodization suffers from one-sidedness and certain deviations from reality. However, the number and significance of such deviations can be radically diminished as the effectiveness of periodization is directly connected with its author's understanding of the rules and peculiarities of this methodological procedure. In this paper we would like to suggest a model of periodization of history based on our theory of historical process. We shall also demonstrate some possibilities of mathematical modeling for the problems concerning the macroperiodization of the world historical process. This analysis identifies a number of cycles within this process and suggests its generally hyperexponential shape, which makes it possible to propose a number of forecasts concerning the forthcoming decades. *

Sketch of history of mathematics in Nizhny Novgorod

In his reasoning concerning the relationship between surface or visible superficies (understood as the boundary or the limit of a body) and color (*De sensu* 439a19–b17), Aristotle asserts that the Pythagoreans called the surface (ἐπιφάνεια) color (χροιά), i.e. that they made no terminological difference between the former and the latter. In the scholarship on early Pythagoreans, this passage has been usually used as an indirect proof for the inaccuracy of attribution to the early Pythagoreans (1) of the abstract notion of surface (as found in Plato and Euclid), and thereby (2) of various forms of “derivation theory”. We argue that the colour-surface-limit doctrine has great significance for the understanding of the early Pythagorean concept of a number, since they articulated it, in various ways, precisely through the notion of a limit.

Materials for the International Conference Analytical and Computational Methods in Probability Theory and its Applications (ACMPT-2017)

The scientific publication presents the materials of the International Scientific Conference "Analytical and Computational Methods in Probability Theory and Its Applications" in the following main areas:

- Analytical methods in probability theory and its applications;

- Computational methods in probability theory and its applications;

- Asymptotic methods in analysis;

- History of Mathematics

The collection is intended for scientists and specialists in the field of probability theory and its applications.

ISBN 978-5-209-08291-0

We consider certain spaces of functions on the circle, which naturally appear in harmonic analysis, and superposition operators on these spaces. We study the following question: which functions have the property that each their superposition with a homeomorphism of the circle belongs to a given space? We also study the multidimensional case.

We consider the spaces of functions on the m-dimensional torus, whose Fourier transform is p -summable. We obtain estimates for the norms of the exponential functions deformed by a C1 -smooth phase. The results generalize to the multidimensional case the one-dimensional results obtained by the author earlier in “Quantitative estimates in the Beurling—Helson theorem”, Sbornik: Mathematics, 201:12 (2010), 1811 – 1836.

We consider the spaces of function on the circle whose Fourier transform is p-summable. We obtain estimates for the norms of exponential functions deformed by a C1 -smooth phase.

Let k be a field of characteristic zero, let G be a connected reductive algebraic group over k and let g be its Lie algebra. Let k(G), respectively, k(g), be the field of k- rational functions on G, respectively, g. The conjugation action of G on itself induces the adjoint action of G on g. We investigate the question whether or not the field extensions k(G)/k(G)^G and k(g)/k(g)^G are purely transcendental. We show that the answer is the same for k(G)/k(G)^G and k(g)/k(g)^G, and reduce the problem to the case where G is simple. For simple groups we show that the answer is positive if G is split of type A_n or C_n, and negative for groups of other types, except possibly G_2. A key ingredient in the proof of the negative result is a recent formula for the unramified Brauer group of a homogeneous space with connected stabilizers. As a byproduct of our investigation we give an affirmative answer to a question of Grothendieck about the existence of a rational section of the categorical quotient morphism for the conjugating action of G on itself.

Let G be a connected semisimple algebraic group over an algebraically closed field k. In 1965 Steinberg proved that if G is simply connected, then in G there exists a closed irreducible cross-section of the set of closures of regular conjugacy classes. We prove that in arbitrary G such a cross-section exists if and only if the universal covering isogeny Ĝ → G is bijective; this answers Grothendieck's question cited in the epigraph. In particular, for char k = 0, the converse to Steinberg's theorem holds. The existence of a cross-section in G implies, at least for char k = 0, that the algebra k[G]G of class functions on G is generated by rk G elements. We describe, for arbitrary G, a minimal generating set of k[G]G and that of the representation ring of G and answer two Grothendieck's questions on constructing generating sets of k[G]G. We prove the existence of a rational (i.e., local) section of the quotient morphism for arbitrary G and the existence of a rational cross-section in G (for char k = 0, this has been proved earlier); this answers the other question cited in the epigraph. We also prove that the existence of a rational section is equivalent to the existence of a rational W-equivariant map T- - - >G/T where T is a maximal torus of G and W the Weyl group.