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Inverse problems on star-type graphs: differential operators of different orders on different edges

Vyacheslav Yurko (2014)

Open Mathematics

We study inverse spectral problems for ordinary differential equations on compact star-type graphs when differential equations have different orders on different edges. As the main spectral characteristics we introduce and study the so-called Weyl-type matrices which are generalizations of the Weyl function (m-function) for the classical Sturm-Liouville operator. We provide a procedure for constructing the solution of the inverse problem and prove its uniqueness.

La g -fonction de Littlewood-Paley associée à un opérateur différentiel singulier sur ( 0 , )

A. Achour, K. Trimeche (1983)

Annales de l'institut Fourier

Dans son livre [H. Stein, Ann. of Math. Studies, 63, Princeton Univ. Press, (1970)] E. Stein associe à tout opérateur de Sturm-Liouville la g -fonction de Littlewood-Paley et conjecture que, pour tout p dans l’intervalle ] 1 , [ , il existe deux constantes C p et D p telles que : C p f p g ( f ) p D p f p . On démontre ces inégalités pour une classe d’opérateurs différentiels singuliers sur ] 0 , [ et on énonce alors un résultat sur les multiplicateurs concernant ces opérateurs.

Lipschitzian norm estimate of one-dimensional Poisson equations and applications

Hacene Djellout, Liming Wu (2011)

Annales de l'I.H.P. Probabilités et statistiques

By direct calculus we identify explicitly the lipschitzian norm of the solution of the Poisson equation in terms of various norms of g, where is a Sturm–Liouville operator or generator of a non-singular diffusion in an interval. This allows us to obtain the best constant in the L1-Poincaré inequality (a little stronger than the Cheeger isoperimetric inequality) and some sharp transportation–information inequalities and concentration inequalities for empirical means. We conclude with several illustrative...

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