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This paper deals with radial and non-radial solutions for local and nonlocal Liouville type equations. At first non-degenerate and degenerate mean field equations are studied and radially symmetric solutions to the Dirichlet problem for them are written into explicit form. Non-radial solution is constructed in the case of Blaschke type nonlinearity. The Cauchy boundary value problem for nonlinear Laplace equation with several exponential nonlinearities is considered and C^2 smooth monotonically decreasing radial solution u ( r ) is found. Moreover, u ( r ) has logarithmic growth at ∞. Our results are applied to the differential geometry, more precisely, minimal non-superconformal degenerate two dimensional surfaces are constructed in R^4 and their Gaussian, respectively normal curvatures are written into explicit form. At the end of the paper several examples of local Liouville type PDE with radial coefficients which do not have radial solutions are given.

[Popivanov Petar; Попиванов Петър] 2010 Mathematics Subject Classification: 35J05, 35J65, 35J67, 30D55.

[Popivanov Petar; Попиванов Петър] Explicit formulas to the solutions of several equations of mathematical physics including semilinear multidimensional Klein-Gordon equation, the wave equation, Kadomtsev-Petviashvili equation and cubic first order hyperbolic pseudodifferential equation are proposed. 2000 Mathematics Subject Classification: 35C05, 35L05, 35Q53, 35S10.

This book deals with equations of mathematical physics as the different modifications of the KdV equation, the Camassa-Holm type equations, several modifications of Burger's equation, the Hunter-Saxton equation, conservation laws equations and others. The equations originate from physics but are proposed here for their investigation via purely mathematical methods in the frames of university courses. More precisely, we propose classification theorems for the traveling wave solutions for a sufficiently large class of third order nonlinear PDE when the corresponding profiles develop different kind of singularities (cusps, peaks), existence and uniqueness results, etc. The orbital stability of the periodic solutions of traveling type for mKdV equations are also studied. Of great interest too is the interaction of peakon type solutions of the Camassa-Holm equation and the solvability of the classical and generalized Cauchy problem for the Hunter-Saxton equation. The Riemann problem for special systems of conservation laws and the corresponding -shocks are also considered. As it concerns numerical methods we apply the CNN approach. The book is addressed to a broader audience including graduate students, Ph.D. students, mathematicians, physicist, engineers and specialists in the domain of PDE.