# Matematychni Studii Vol. 51, No.1, 2019

## CONTENTS

 Title 1
 Contents 2
 An alternative look at the structure of graph inverse semigroups Bardyla S. 3
 Sequential coarse structures of topological groups Protasov I. V. 12
 On $\varepsilon$-Friedrichs inequalities and its application Buhrii O. M. 19
 Compositions of Dirichlet series similar to the Hadamard compositions, and convergence classes Mulyava O. M., Sheremeta M. M. 25
 Weakened problem on extremal decomposition of the complex plane Bakhtin A. K., Denega I. V. 35
 Weakly weighted-sharing and uniqueness of homogeneous differential polynomials Pramanik D. C., Roy Ja. 41
 On interpolation problem with derivative in a space of entire functions with fast-growing interpolation knots Vynnyts'kyi B. V., Sheparovych I. B. 50
 The Fourier problem for weakly nonlinear integro-differential elliptic-parabolic systems Bokalo M. M., Skira I. V. 59
 The best approximations and widths of the classes of periodical functions of one and several variables in the space $B_{\infty, 1}$(in Ukrainian) Hembarskyi M. V., Hembarska S. B., Solich K. V. 74
 Linear expand-contract plasticity of ellipsoids in separable Hilbert spaces Zavarzina O. O. 86
 Matrix representation of Taylor's formula for mappings in finite dimensional spaces Senio P. S. 92

## PROBLEM SECTION

 On some problem for entire functions of unbounded index in any direction Hural I. M. 107

## CHRONICLE

 Kyrychenko Volodymyr Vasylovych (17 June 1942 -- 2 April 2019) 111

Matematychni Studii
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