Institute of Mathematics AS CR, v. v. i.
Not a member yet
44818 research outputs found
Sort by
The Beginnings of Solar Observations at the Skalnaté Pleso Observatory
No full textsummary:Článok sa detailne venuje prvému pozorovaniu Slnka na Observatóriu Skalnaté Pleso, ktoré vykonal 19. septembra 1943 dr. Antonín Bečvář - zakladateľ a prvý riaditeľ observatória. Pretože v príslušnom protokole je ako pozorovacie miesto uvedené Štrbské Pleso a Skalnaté Pleso, zvláštna pozornosť je venovaná lokalizácii a okolnostiam pozorovaní pred a po 19. septembri 1943 s dôrazom na argumenty jednoznačne svedčiace o tom, že pozorovanie v tomto a nasledujúcich dňoch boli získané na Observatóriu Skalnaté Pleso
On sparsity of approximate solutions to max-plus linear systems
Get PDFsummary:When a system of one-sided max-plus linear equations is inconsistent, the approximate solutions within an admissible error bound may be desired instead, particularly with some sparsity property. It is demonstrated in this paper that obtaining the sparsest approximate solution within a given error bound may be transformed in polynomial time into the set covering problem, which is known to be NP-hard. Besides, the problem of obtaining the sparsest approximate solution within a given error bound may be reformulated as a polynomial-sized mixed integer linear programming problem, which may be regarded as a special scenario of the facility location-allocation problem. By this reformulation approach, this paper reveals some interesting connections between the sparsest approximate solution problems in max-plus algebra and some well known problems in discrete and combinatorial optimization
A note on the existence of solutions with prescribed asymptotic behavior for half-linear ordinary differential equations
Get PDFsummary:The half-linear differential equation is considered, where and are positive constants and is a real-valued continuous function on . It is proved that, under a mild integral smallness condition of which is weaker than the absolutely integrable condition of , the above equation has a nonoscillatory solution such that and (), and a nonoscillatory solution such that and ()
Some Hölder-logarithmic estimates on Hardy-Sobolev spaces
No full textsummary:We prove some optimal estimates of Hölder-logarithmic type in the Hardy-Sobolev spaces , where , and is either the open unit disk or the annular domain , of the complex space . More precisely, we study the behavior on the interior of of any function belonging to the unit ball of the Hardy-Sobolev spaces from its behavior on any open connected subset of the boundary of with respect to the -norm. Our results can be viewed as an improvement and generalization of those established in S. Chaabane, I. Feki (2009), I. Feki, H. Nfata, F. Wielonsky (2012), I. Feki (2013), I. Feki, H. Nfata (2014). As an application, we establish a logarithmic stability results for the Cauchy problem of the identification of Robin's coefficient by boundary measurements
On linear maps leaving invariant the copositive/completely positive cones
No full textsummary:The objective of this manuscript is to investigate the structure of linear maps on the space of real symmetric matrices that leave invariant the closed convex cones of copositive and completely positive matrices ( and ). A description of an invertible linear map on such that is obtained in terms of semipositive maps over the positive semidefinite cone and the cone of symmetric nonnegative matrices for , with specific calculations for . Preserver properties of the Lyapunov map , the generalized Lyapunov map , and the structure of the dual of the cone (for ) are brought out. We also highlight a different way to determine the structure of an invertible linear map on that leaves invariant the closed convex cone
Local boundedness for minimizers of variational integrals under anisotropic nonstandard growth conditions
No full textsummary:This paper deals with local boundedness for minimizers of vectorial integrals under anisotropic growth conditions by using De Giorgi's iterative method. We consider integral functionals with the first part of the integrand satisfying anisotropic growth conditions including a convex nondecreasing function , and with the second part, a convex lower order term or a polyconvex lower order term. Local boundedness of minimizers is derived
Are zero-symmetric simple nearrings with identity equiprime?
No full textsummary:We show that there exist zero-symmetric simple nearrings with identity, which are not equiprime, solving a longstanding open problem