Sebastian Zając

• PhD
• Professor (Assistant) at SGH Warsaw School of Economics

This paper shows how information about the network’s community structure can be used to define node features with high predictive power for classification tasks. To do so, we define a family of community-aware node features and investigate their properties. Those features are designed to ensure that they can be efficiently computed even for large g...

A community structure that is often present in complex networks plays an important role not only in their formation but also shapes dynamics of these networks, affecting properties of their nodes. In this paper, we propose a family of community-aware node features and then investigate their properties. We show that they have high predictive power f...

A community structure that is often present in complex networks plays an important role not only in their formation but also shapes dynamics of these networks, affecting properties of their nodes. In this paper, we propose a family of community-aware node features and then investigate their properties. We show that they have high predictive power f...

We use principles from the thermodynamics of spacetime to modify the path integral of quantum mechanics. Entropy of the vacuum is interpreted as microstates that correspond to the measure of the path integral. The result is a contribution to the action that is proportional to the Einstein-Hilbert action. Because the contribution is real, not imagin...

https://github.com/sebkaz/RTA_code Rozdział 1 przedstawia dane, zarówno ustrukturyzowane, jak i nieustrukturyzowane, poprzez ich różne obiektowe reprezentacje oraz metody ich programowania w języku Python: od podstawowych pythonowych list przez tablice Numpy, Pandasowe ramki danych aż potensory realizowane przez biblioteki związane z uczeniem głę...

Foreword In the present competitive and efficiency-oriented economic realm, credit scoring plays an important role, impacting numerous aspects of economic activities and driving their successes. From the level of self-employment, through micro, small, medium size and large companies and institutions, to even multinational enterprises and institutio...

Foreword In the present competitive and efficiency-oriented economic realm, credit scoring plays an important role, impacting numerous aspects of economic activities and driving their successes. From the level of self-employment, through micro, small, medium size and large companies and institutions, to even multinational enterprises and institutio...

Oddajemy do rąk czytelników kolejną książkę z serii "Modelowanie dla biznesu". Rozpoczynając wydanie tej serii w 2019 roku, nikt z nas nie zdawał sobie sprawy, że rozpoczniemy wiele działań (w tym wydarzeń naukowo-biznesowych i publikacji) zmierzających do tworzenia pomostu pomiędzy biznesem a nauką.Z perspektywy czasu możemy teraz śmiało dzielić s...

Imposing a family symmetry on the Standard Model in order to reduce the number of its free parameters, due to the Schur’s Lemma, requires an explicit breaking of this symmetry. To avoid the need for this symmetry to break, additional Higgs doublets can be introduced. In such an extension of the Standard Model, we investigate family symmetries of th...

The 'Genus for biomolecules' database (http://genus.fuw.edu.pl) collects information about topological structure and complexity of proteins and RNA chains, which is captured by the genus of a given chain and its subchains. For each biomolecule, this information is shown in the form of a genus trace plot, as well as a genus matrix diagram. We assemb...

Abstract The structure of bonds in biomolecules, such as base pairs in RNA chains or native interactions in proteins, can be presented in the form of a chord diagram. A given biomolecule is then characterized by the genus of an auxiliary two-dimensional surface associated to such a diagram. In this work we introduce the notion of the genus trace, w...

Within the framework of the two-Higgs-doublet model, we attempt to find some discrete, non-Abelian flavor symmetry that could provide an explanation for the masses and mixing matrix elements of leptons. Unlike the Standard Model, currently there is no need for the flavor symmetry to be broken. With the gap program we investigate all finite subgroup...

Within the framework of the two-Higgs Doublet Model (2HDM), we attempt to find some discrete, non-abelian flavour symmetry which could provide an explanation for the masses and mixing matrix elements of leptons. Unlike the Standard Model, currently there is no need for the flavour symmetry to be broken. With the GAP program we investigate all finit...

The Standard Model does not explain the hierarchy problem. Before the discovery of nonzero lepton mixing angle {\theta}13 high hopes in explanation of the shape of the lepton mixing matrix were combined with non abelian symmetries. Nowadays, assuming one Higgs doublet, it is unlikely that this is still valid. Texture zeroes, that are combined with...

In the frame of two Higgs doublet model we try to explain the lepton masses and mixing matrix elements assuming that neutrinos are Dirac particles. Discrete family symmetry groups, which are subgroups of U(3) up to the 1025 order are considered. Like in the one Higgs Standard Model, we found that discrete family symmetries do not give satisfactory...

The Standard Model does not explain the hierarchy problem. Before the discovery of nonzero lepton mixing angle {\theta}13 high hopes in explanation of the shape of the lepton mixing matrix were combined with non abelian symmetries. Nowadays, assuming one Higgs doublet, it is unlikely that this is still valid. Texture zeroes, that are combined with...

In order to explain the fermions’ masses and mixing parameters appearing in the lepton sector of the Standard Model, one proposes the extension of its symmetry. A discrete, non-Abelian subgroup of U(3) is added to the gauge group SU(3) C × SU(2) L × U(1) Y . Apart from that, one assumes the existence of one extra Higgs doublet. This article focuses...

In order to explain the fermions masses and mixing parameters appearing in the lepton sector of the Standard Model, one proposes the extension of its symmetry. A discrete, non-abelian subgroup of $U(3)$ is added to the gauge group $SU(3)_{C}\times SU(2)_{L}\times U(1)_{Y}$ . Apart from that, one assumes the existence of one extra Higgs doublet. Thi...

In the framework of a two Higgs doublet model, we try to explain lepton masses and mixing matrix elements assuming that neutrinos are Dirac particles. Discrete family symmetry groups, which are subgroups of U(3) up to the order of 1025 are considered. Like in the Standard Model with one Higgs doublet, we found that discrete family symmetries do not...

A brief discussion about the current status of the search for the possible finite symmetry of a leptonic mass matrix is presented. Possible extensions of the models of leptons that can describe the masses and mixing elements are discussed.

From the new existing data with not vanishing theta13 mixing angle we determine the possible shape of the Majorana neutrino mass matrix. We assume that CP symmetry is broken and all Dirac and Majorana phases are taken into account. Two possible approaches "bottom-up" and "top down" are presented. The problem of unphysical phases is examined in deta...

The subjects of the paper are the likelihood method (LM) and the expected Fisher information (FI) considered from the point od view of the construction of the physical models which originate in the statistical description of phenomena. The master equation case and structural information principle are derived. Then, the phenomenological description...

The process of the neutrino production, oscillation in the vacuum or in matter, and detection in the case of interactions which are beyond the Standard Model is considered. Neutrino states are described by the density matrix. The final neutrino production rate does not factorize. The known Maki–Nakagawa–Sakata neutrino states and the factorized pro...