Sergienko, I. V.; Lytvyn, O. M.; Lytvyn, O. O.; Tkachenko, O. V.; Grytsaĭ, O. L. Hermitian type interpolation at point of the system of disjoint lines on a surface. (Ukrainian. English summary) Zbl 1324.65016 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2015, No. 2, 38-43 (2015). MSC: 65D05 65D07 PDFBibTeX XMLCite \textit{I. V. Sergienko} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2015, No. 2, 38--43 (2015; Zbl 1324.65016) Full Text: DOI
Lytvyn, O. M.; Lytvyn, O. O.; Tkachenko, O. V.; Grytsaĭ, O. L. Hermitian interlineation of functions of two variables on the given system of disjoint lines with preservation of the class \(C^r(\mathbb R^2)\). (Ukrainian. English summary) Zbl 1313.65039 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2014, No. 7, 53-59 (2014). MSC: 65D25 65D05 41A63 41A27 PDFBibTeX XMLCite \textit{O. M. Lytvyn} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2014, No. 7, 53--59 (2014; Zbl 1313.65039) Full Text: DOI
Sergienko, I. V.; Lytvyn, O. M.; Lobanova, L. S.; Zaluzhna, G. V. Analysis of the computing power of the interlineation finite-element method of solution of the non-stationary heat conduction problem. (Ukrainian. English summary) Zbl 1313.65268 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2014, No. 3, 43-50 (2014). MSC: 65M60 35K05 PDFBibTeX XMLCite \textit{I. V. Sergienko} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2014, No. 3, 43--50 (2014; Zbl 1313.65268) Full Text: DOI
Lytvyn, O. M.; Lytvyn, O. O.; Tkachenko, O. V.; Grytsaĭ, O. L. Recovery of the functions of two variables with preservation of the class \(C^r(R^2)\) with the help of their traces and the traces of their derivatives up to a fixed order on the given curve. (Ukrainian. English summary) Zbl 1313.65038 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2014, No. 2, 50-55 (2014). MSC: 65D25 65D05 41A63 41A27 PDFBibTeX XMLCite \textit{O. M. Lytvyn} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2014, No. 2, 50--55 (2014; Zbl 1313.65038) Full Text: DOI
Sergienko, I. V.; Lytvyn, O. M.; Lytvyn, O. O. The method of interlineation of the vector- functions \(\vec{w}(x,y,z,t)\) on a system of vertical straight lines and its application to the interhole seismic tomography. (Ukrainian. English summary) Zbl 1289.86008 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2013, No. 3, 35-40 (2013). MSC: 86A22 PDFBibTeX XMLCite \textit{I. V. Sergienko} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2013, No. 3, 35--40 (2013; Zbl 1289.86008)
Lytvyn, O. M.; Pershina, Yu. I. Approximation of discontinuous functions by discontinuous splines on a rectangle with one curvilinear side. (Ukrainian. English summary) Zbl 1289.41004 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2013, No. 2, 30-35 (2013). MSC: 41A05 41A15 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{Yu. I. Pershina}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2013, No. 2, 30--35 (2013; Zbl 1289.41004)
Lytvyn, O. M.; Pershina, Yu. I. Approximation of discontinuous functions by piecewise linear interpolational discontinuous splines on triangular grid of nodes. (Ukrainian. English summary) Zbl 1249.65026 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2012, No. 1, 38-43 (2012). MSC: 65D07 65D10 65D05 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{Yu. I. Pershina}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2012, No. 1, 38--43 (2012; Zbl 1249.65026)
Lytvyn, O. M.; Lobanova, L. S. About one method of construction of exact solutions of a boundary-value problem for a differential equation of elliptic type in the areas of complicated forms. (Ukrainian. English summary) Zbl 1249.65266 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2011, No. 7, 37-41 (2011). MSC: 65N40 35J25 65D07 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{L. S. Lobanova}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2011, No. 7, 37--41 (2011; Zbl 1249.65266)
Lytvyn, O. M.; Pershina, Y. I. Solution of a three-dimensional problem in computer tomography with the use of a small number of tomograms. (Ukrainian. English summary) Zbl 1233.92051 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2011, No. 5, 40-44 (2011). MSC: 92C55 94A08 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{Y. I. Pershina}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2011, No. 5, 40--44 (2011; Zbl 1233.92051)
Sergienko, I. V.; Lytvyn, O. M.; Gulik, L. I.; Tkachenko, O. V.; Chernyak, O. O. A mathematical model of the surface of a body in implicit form on the basis of the interflatation of functions. (Ukrainian. English summary) Zbl 1240.26034 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2011, No. 3, 40-44 (2011). MSC: 26B35 PDFBibTeX XMLCite \textit{I. V. Sergienko} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2011, No. 3, 40--44 (2011; Zbl 1240.26034)
Sergienko, I. V.; Lytvyn, O. M.; Tkachenko, O. V.; Pasichnyk, V. O.; Chernyak, O. O. A mathematical model of 2D curve in an implicit form on the basis of the interlineation of functions. (Ukrainian. English summary) Zbl 1224.65042 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2010, No. 5, 45-49 (2010). MSC: 65D17 PDFBibTeX XMLCite \textit{I. V. Sergienko} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2010, No. 5, 45--49 (2010; Zbl 1224.65042)
Lytvyn, O. M.; Nechujviter, O. P. About one cubature formula for calculation of two-dimensional Fourier coefficients with the use of interlineations of functions. (Ukrainian. English summary) Zbl 1224.41036 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2010, No. 3, 24-29 (2010). MSC: 41A15 42A15 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{O. P. Nechujviter}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2010, No. 3, 24--29 (2010; Zbl 1224.41036)
Lytvyn, O. M.; Nef’odova, I. V. Some aspects of numerical realization of the finite element method with optimal choice of parameters, basic functions, and coordinates of knots of elements. (Ukrainian. English summary) Zbl 1199.65264 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2009, No. 4, 33-38 (2009). MSC: 65L60 65L10 34B05 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{I. V. Nef'odova}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2009, No. 4, 33--38 (2009; Zbl 1199.65264)
Lytvyn, O. M.; Shtepa, N. I. Simulation of distribution of minerals with the help of the interlineation of functions of three variables. (Ukrainian. English summary) Zbl 1199.41054 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2009, No. 2, 36-40 (2009). MSC: 41A15 42C05 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{N. I. Shtepa}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2009, No. 2, 36--40 (2009; Zbl 1199.41054)
Lytvyn, O. M.; Kulyk, S. I. Interlineation of the functions of two variables with the use of fundamental splines. (Ukrainian. English summary) Zbl 1164.41318 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2008, No. 7, 26-30 (2008). MSC: 41A15 41A25 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{S. I. Kulyk}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2008, No. 7, 26--30 (2008; Zbl 1164.41318)
Lytvyn, O. M.; Shtepa, N. I. Interlineation operators of the Lagrange type on a system of mutually perpendicular straight lines with the use of generalized polynomials. (Ukrainian. English summary) Zbl 1164.41357 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2008, No. 5, 25-29 (2008). MSC: 41A99 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{N. I. Shtepa}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2008, No. 5, 25--29 (2008; Zbl 1164.41357)
Lytvyn, O. M. Interpolation of ordinary differential operators in Hilbert spaces. (Ukrainian. English summary) Zbl 1164.47341 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2008, No. 2, 25-29 (2008). MSC: 47E05 47A58 PDFBibTeX XMLCite \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2008, No. 2, 25--29 (2008; Zbl 1164.47341)
Lytvyn, O. M. The approximation of ordinary differential operators. (Ukrainian. English summary) Zbl 1144.47317 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2007, No. 8, 16-20 (2007). MSC: 47E05 47A58 PDFBibTeX XMLCite \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2007, No. 8, 16--20 (2007; Zbl 1144.47317)
Lytvyn, O. M. Interpolation of differential operators with partial derivatives. (Ukrainian. English summary) Zbl 1144.47318 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2007, No. 7, 7-11 (2007). MSC: 47F05 47A58 PDFBibTeX XMLCite \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2007, No. 7, 7--11 (2007; Zbl 1144.47318)
Lytvyn, O. M. The interpolation of ordinary differential operators. (Ukrainian. English summary) Zbl 1144.47316 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2007, No. 6, 19-23 (2007). MSC: 47E05 47A57 PDFBibTeX XMLCite \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2007, No. 6, 19--23 (2007; Zbl 1144.47316)
Lytvyn, O. M.; Lepetchenko, G. V. On an approach to the construction of optimum basis functions in the finite-element method (triangular elements). (Ukrainian. English summary) Zbl 1122.65402 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2006, No. 7, 18-22 (2006). MSC: 65N30 35J25 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{G. V. Lepetchenko}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2006, No. 7, 18--22 (2006; Zbl 1122.65402)
Lytvyn, O. M.; Nechujviter, O. P. A cubature formula optimal by order of accuracy for calculation of double integrals of rapidly oscillating functions on the basis of spline-interlineation. (Ukrainian. English summary) Zbl 1099.65025 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2006, No. 6, 9-13 (2006). MSC: 65D32 41A55 41A63 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{O. P. Nechujviter}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2006, No. 6, 9--13 (2006; Zbl 1099.65025)
Lytvyn, O. M.; Pershyna, Yu. I. A mathematical model of restoration of 3D objects by their tomograms on a system of three groups of crossed planes by using the interflation of functions. (Ukrainian. English summary) Zbl 1092.68110 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 8, 67-71 (2005). MSC: 68U10 68U05 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{Yu. I. Pershyna}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 8, 67--71 (2005; Zbl 1092.68110)
Lytvyn, O. M. On an error estimate for the approximation of differentiable functions by linear splines in the norm in the \(W_2^1[0,1]\) norm. (Ukrainian. English summary) Zbl 1098.41008 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 7, 22-26 (2005). MSC: 41A15 41A25 PDFBibTeX XMLCite \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 7, 22--26 (2005; Zbl 1098.41008)
Lytvyn, O. M.; Pasichnyk, V. O. Optimization of the number of vertical sections of the surface of a dummy and their arrangement upon a simulation. (Ukrainian. English summary) Zbl 1097.41500 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 6, 63-68 (2005). MSC: 41A99 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{V. O. Pasichnyk}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 6, 63--68 (2005; Zbl 1097.41500)
Lytvyn, O. M.; Pershyna, Yu. I. A mathematical model of the restoration of the internal structure of a 3D object by its known tomograms by using the interflation of functions. (Ukrainian. English summary) Zbl 1067.68164 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 1, 20-24 (2005). MSC: 68U05 68U10 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{Yu. I. Pershyna}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2005, No. 1, 20--24 (2005; Zbl 1067.68164)
Gulik, L. I.; Lytvyn, O. M. Interlineation of functions of 3 variables on a system of orthogonal straight lines. (Ukrainian. English summary) Zbl 1066.41009 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2004, No. 11, 16-22 (2004). MSC: 41A15 41A05 42C05 PDFBibTeX XMLCite \textit{L. I. Gulik} and \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2004, No. 11, 16--22 (2004; Zbl 1066.41009)
Lytvyn, O. M.; Pasichnyk, V. O. Optimization of the number of horizontal cross sections of the dummy surface and their arrangement on simulation. (Ukrainian. English summary) Zbl 1077.93528 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2004, No. 2, 66-71 (2004). MSC: 93C95 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{V. O. Pasichnyk}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2004, No. 2, 66--71 (2004; Zbl 1077.93528)
Gulik, L. I.; Lytvyn, O. M. On an approach to solution of a Dirichlet boundary-value problem for the Poisson equation with the use of interlineations. (Ukrainian. English summary) Zbl 1055.65127 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2004, No. 1, 13-18 (2004). MSC: 65N30 65F10 35J05 PDFBibTeX XMLCite \textit{L. I. Gulik} and \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2004, No. 1, 13--18 (2004; Zbl 1055.65127)
Lytvyn, O. M.; Nosov, K. V. A theorem on the convergence of the “flip-flop” procedure in a method involving nonlinear integro-differential equations. (Ukrainian. English summary) Zbl 1038.65146 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 12, 17-21 (2003). MSC: 65R20 45G15 45J05 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{K. V. Nosov}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 12, 17--21 (2003; Zbl 1038.65146)
Babenko, K. E.; Lytvyn, O. M. On the numerical realization of the Fourier direct method in computer tomography. (Ukrainian. English summary) Zbl 1038.65140 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 11, 7-12 (2003). MSC: 65R10 44A12 92C55 65D32 PDFBibTeX XMLCite \textit{K. E. Babenko} and \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 11, 7--12 (2003; Zbl 1038.65140) Full Text: DOI
Babenko, K. E.; Lytvyn, O. M.; Mezhuev, V. I. A mathematical model of computer-based tomography on the basis of the Fourier method and the interlineation of functions. (Ukrainian. English summary) Zbl 1038.65141 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 10, 70-74 (2003). MSC: 65R10 65T50 44A12 92C55 PDFBibTeX XMLCite \textit{K. E. Babenko} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 10, 70--74 (2003; Zbl 1038.65141)
Baranova, T. A.; Lytvyn, O. M. On the construction of the structure of an approximate solution in the optimum finite element method for polygonal domains. (Ukrainian. English summary) Zbl 1038.65120 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 9, 7-11 (2002). MSC: 65N30 35J25 PDFBibTeX XMLCite \textit{T. A. Baranova} and \textit{O. M. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2003, No. 9, 7--11 (2002; Zbl 1038.65120)
Lytvyn, O. M.; Mikhalkin, V. V. Error estimation for a plane problem of computer tomography by using piecewise constant splines. (Ukrainian. English summary) Zbl 1006.65140 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2002, No. 5, 31-35 (2002). MSC: 65R10 44A12 92C55 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{V. V. Mikhalkin}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2002, No. 5, 31--35 (2002; Zbl 1006.65140)
Drobot, E. I.; Lytvyn, O. M.; Sergijenko, I. V. A numerical realization of the LIDE method for a nonsteady heat equation with three spatial variables. (Ukrainian. English summary) Zbl 0961.65090 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2000, No. 2, 67-73 (2000). Reviewer: Isaac Yevzerov (Kyïv) MSC: 65M60 65M15 35K05 PDFBibTeX XMLCite \textit{E. I. Drobot} et al., Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 2000, No. 2, 67--73 (2000; Zbl 0961.65090)
Lytvyn, O. M.; Lytvyn, O. O. A method of solution of a plane problem of \(X\)-ray computer tomography based on the use of interlineation of functions. (Ukrainian) Zbl 0931.65125 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 12, 29-33 (1998). MSC: 65R10 92C55 44A12 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{O. O. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 12, 29--33 (1998; Zbl 0931.65125)
Lytvyn, O. M.; Lytvyn, O. O. Interpolation operators for functions of two variables with given Fourier coefficients. (Ukrainian) Zbl 1029.42500 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 6, 37-43 (1998). MSC: 42A15 42A16 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{O. O. Lytvyn}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 6, 37--43 (1998; Zbl 1029.42500)
Lytvyn, O. M.; Nechujviter, O. P. Cubature formulas for calculation of the Fourier coefficients of functions of two variables by using spline-interlineation. (Ukrainian) Zbl 0931.65144 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 1, 23-28 (1998). MSC: 65T40 42B05 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{O. P. Nechujviter}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 1, 23--28 (1998; Zbl 0931.65144)
Lytvyn, O. M.; Nosov, K. V. A general solution for a symmetric-boundary system of fourth-order differential equations appearing in the optimal method of finite elements. (Ukrainian) Zbl 0931.65113 Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 10, 25-31 (1998). Reviewer: I.O.Parasyuk (Kyïv) MSC: 65N30 35J40 65L10 34B05 PDFBibTeX XMLCite \textit{O. M. Lytvyn} and \textit{K. V. Nosov}, Dopov. Nats. Akad. Nauk Ukr., Mat. Pryr. Tekh. Nauky 1998, No. 10, 25--31 (1998; Zbl 0931.65113)