Some sharp Landau-Kolmogorov–Nagy-type inequalities in Sobolev spaces of multivariate functions
DOI:
https://doi.org/10.3842/umzh.v75i10.7680Keywords:
Nagy and Landau -- Kolmogorov type inequality, charge, gradient, mixed derivativeAbstract
UDC 517.5
For a function f from the Sobolev space W1,p(C), where C⊂Rd is an open convex cone, we establish a sharp inequality estimating ‖ via the L_{p}-norm of its gradient and a seminorm of the function. With the help of this inequality, we prove a sharp inequality estimating the {L_{\infty}}-norm of the Radon-Nikodym derivative of a charge defined on Lebesgue measurable subsets of C via the L_p-norm of the gradient of this derivative and the seminorm of the charge. In the case where C=R_+^m\times R^{d-m}, 0\le m\le d, we obtain inequalities estimating the {L_{\infty}}-norm of a mixed derivative of the function f\colon C\to R via its {L_{\infty}}-norm and the L_p-norm of the gradient of mixed derivative of this function.
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