A graph G = (V;E) is word-representable if there is a word w over the alphabet V such that x and y alternate in w if and only if the edge (x; y) is in G. It is known  that all 3-colourable graphs are word-representable, while among those with a higher chromatic number some are word-representable while others are not.
There has been some recent research on the word-representability of polyomino triangulations. Akrobotu et al.  showed that a triangulation of a convex polyomino is word-representable if and only if it is 3-colourable; and Glen and Kitaev  extended this result to the case of a rectangular polyomino triangulation when a single domino tile is allowed.
It was shown in  that a near-triangulation is 3-colourable if and only if it is internally even. This paper provides a much shorter and more elegant proof of this fact, and also shows that near-triangulations are in fact a generalization of the polyomino triangulations studied in  and , and so we generalize the results of these two papers, and solve all open problems stated in .
Economic growth is one of the most studied topics in the literature in the field due to its significant role in the development of each country. Studies divide economic determinants into two categories based on their influence on economic growth: endogenous and exogenous. The study aims to estimate economic growth against two types of determinants for Romania and Central and Eastern European countries using data for 1995-2017 in order to compare the two cases. For Romania, we used time series specific methods (e.g. stationarity checking using Augmented Dickey-Fuller test, OLS model). In case of Central and Eastern European countries, we employed methods specific for panel data (e.g. estimation of the OLS general model, fixed effects model, random effects model, and feasible generalized least squares model). The results showed that in Romania, in the studied period, only the exogenous determinants (e.g. high technology exports) have a significant influence on economic growth, while Central and Eastern European countries were influenced by both types of determinants (e.g. life expectancy, foreign direct investments). In case of Romania, foreign direct investment did not represent a significant determinant for economic growth during 1995-2017 due to slower transition from communist regime to market economy.
Liviu-Stelian Begu, Simona-Andreea Apostu and Andreea-Oana Enache
The phenomenon of corruption is known all over the world, and its intensity varies according to economic, behavioral and educational factors. Transparency International is a global civil society that carries out regular opinion surveys and publishes the perceptions of corruption in countries around the world. This index identifies the level of corruption perceived in the world and contributes achieving a ranking of countries in this regard. The corruption perception index should be correlated with economic situation of a country. The economic situation of a country can be reflected by GDP and unemployment rate. The purpose of this study is to determine whether the index of corruption is influenced by the economic situation of a country, so the study analyses the corruption perception index, GDP and unemployment rate, establishing whether there is a link between them.
Permutations are frequently used in solving the genome rearrangement problem, whose goal is finding the shortest sequence of mutations transforming one genome into another. We introduce the Deletion-Insertion model (DI) to model small-scale mutations in species with linear chromosomes, such as humans. Applying one restriction to this model, we obtain the transposition model for genome rearrangement, which was shown to be NP-hard in . We use combinatorial reasoning and permutation statistics to develop a polynomial-time algorithm to approximate the minimum number of transpositions required in the transposition model and to analyze the sharpness of several bounds on transpositions between genomes.
Tatyana Strohonova, Maria Bondar and Suren Varzhapetian
There has been a shift in medicine from relying on clinical biomarkers to including patient-reported outcome measures. From a healthcare perspective, health-related quality of life (HRQOL) measures can be used to enhance patient care and reducing treatment cost for patients. Given the possible importance of Medical Outcome Study in medicine, and the conflicting reports in literature about its use in healthcare, it is important to identify its utility within the medical community.
In this study 150 people were recruited prospectively from patients at the Hospital and the emergency сenter №1 in Zaporizhzhya, Ukraine. Four groups were formed. The inclusion criteria to group were different comorbid pathology of osteoarthrosis. We assessed patients HRQOL SF-36 SF-36 changes before and after pharmacotherapy (over 1 year), than it were compared with the control group.
The validity of the construct has been analyzed by discriminant analysis. To assess SF-36 ability identifying discriminating functions were developed, determine its prediction value, define which scales of SF-36 are the best predictors for every groups. In addition, canonical analysis demonstrates SF-36 ability to estimate effect of pharmacotherapy.
Statistical analysis show that all indices quality of life through SF – 36 scales except of third (physical role functioning, physical functioning, emotional role functioning) have prognostic value (p>0.05) and validity of SF-39 scales for examination of the patients with coexisting disease is statistically significant(p<0.05).
Simona-Andreea Apostu, Mihaela Mihai, Valentina Vasile, Manuela-Violeta Tureatca and Valentin Sava
The fiscal analysis is an important research topic, aiming at identifying/creating fair fiscal systems, which can respond to requests coming from both the state (which needs revenue to finance various public projects) and from taxpayers. The economic agents, but also the taxpayers will always want a reduction of the taxes, and the public decider aims to increase the revenues attracted to the budget through (higher) taxes. An optimal tax system could be characterized by taxes that produce minimal effects of distorting the behavior of taxpayers, as well as a positive impact on the development of society.
The phenomenon of globalization has greatly influenced migration in recent years in the European Union. In this article we aim to analyze the benefits of migration in the economy by emphasizing the impact of remittances on the economic development of a country. Remittances are considered as an external source of important, stable funds that help the economic development of a country. We identify also the macroeconomic determinants of remittances. For the statistical and econometric analysis of these factors, we have chosen to use the Panel Data Regression for the countries of the European Union. To analyze the benefits of remittances, the most appropriate macroeconomic indicator is GDP. So in the first part of the article we will present the impact of globalization and migration on remittances, and in the second part we will highlight the economic growth through the presence of remittances. This article examines the role of migrants as a particular segment of the market and as a resource for development. All aspects to be analyzed will outline an overview of population emigration and factors that influence the development of the economy at a time when globalization is on the rise.
Support Vector Machine model is one of the most intensive used text data classifiers ever since the moment of its development. However, its performance depends not only on its features but also on data preprocessing and model tuning. The main purpose of this paper is to compare the efficiency of more Support Vector Machine models using both TF-IDF approach and Word2Vec and Doc2Vec neural networks for text data representation. Besides the data vectorization process, I try to enhance the models’ efficiency by identifying which kind of kernel fits better the data or if it is just better to opt for the linear case. My results prove that for the “Reuters 21578” dataset, nonlinear Support Vector Machine is more efficient when the conversion of text data into numerical attributes is realized using Word2Vec models instead of TF-IDF and Doc2Vec representations. When it is considered that data meet linear separability requirements, TF-IDF representation outperforms all other options. Surprisingly, Doc2Vec models have the lowest performance and only in terms of computational cost they provide satisfactory results. This paper proves that while Word2Vec models are truly efficient for text data representation, Doc2Vec neural networks are unable to exceed even TF-IDF index representation. This evidence contradicts the common idea according to which Doc2Vec models should provide a better insight into the training data domain than Word2Vec models and certainly than the TF-IDF index.
The economic and social transition affected the population and the demographic phenomena in all the ex-communist countries. Immigration can be considered as a potential solution to the problem of population aging. But here too, it must be born in mind that immigrants may not properly adapt to the new labor market they have entered, if they come from very different cultures. Almost all the countries that have migrants, offer residence permits only to those who bring highly qualified workforce, while the legal possibilities of immigration of the unskilled workers are diminishing. Therefore, the demographic perspectives are not the most optimistic. The forecasts developed by specialists reveal dramatic future developments for the population of Romania. The factors that can cause a person to migrate are of several types. In this study it will be shown that migration is the result of several individual actions of analysis, people evaluating both the benefits and the risks involved by a possible migration.
This paper basically completes a project to enumerate permutations avoiding a triple T of 4-letter patterns, in the sense of classical pattern avoidance, for every T. There are 317 symmetry classes of such triples T and previous papers have enumerated avoiders for all but 14 of them. One of these 14 is conjectured not to have an algebraic generating function. Here, we find the generating function for each of the remaining 13, and it is algebraic in each case.