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This article is cited in 1 scientific paper (total in 1 paper)
Research Papers
Regularity issues for semilinear PDE-s (a narrative approach)
H. Shahgholian Department of Mathematics, Royal Institute of Technology, 100 44 Stockholm, Sweden
Abstract:
Occasionally, solutions of semilinear equations have better (local) regularity properties than the linear ones if the equation is independent of space (and time) variables. The simplest example, treated by the current author, was that the solutions of $\Delta u=f(u)$, with the mere assumption that $f'\geq-C$, have bounded second derivatives. In this paper, some aspects of semilinear problems are discussed, with the hope to provoke a study of this type of problems from an optimal regularity point of view. It is noteworthy that the above result has so far been undisclosed for linear second order operators, with Hölder coefficients. Also, the regularity of level sets of solutions as well as related quasilinear problems are discussed. Several seemingly plausible open problems that might be worthwhile are proposed.
Keywords:
pointwise regularity, Laplace equation, divergence type equations, free boundary problems.
Received: 02.03.2015
Citation:
H. Shahgholian, “Regularity issues for semilinear PDE-s (a narrative approach)”, Algebra i Analiz, 27:3 (2015), 311–325; St. Petersburg Math. J., 27:3 (2016), 577–587
Linking options:
https://www.mathnet.ru/eng/aa1446 https://www.mathnet.ru/eng/aa/v27/i3/p311
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