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We are concerned with the optimal constants: in the Korn inequality under tangential boundary conditions on bounded sets $Omega subset mathbb{R}^n$, and in the geometric rigidity estimate on the whole $mathbb{R}^2$. We prove that the latter constant equals $sqrt{2}$, and we discuss the relation of the former constants with the optimal Korns constants under Dirichlet boundary conditions, and in the whole $mathbb{R}^n$, which are well known to equal $sqrt{2}$. We also discuss the attainability of these constants and the structure of deformations/displacement fields in the optimal sets.
We prove optimal boundary regularity for bounded positive weak solutions of fast diffusion equations in smooth bounded domains. This solves a problem raised by Berryman and Holland in 1980 for these equations in the subcritical and critical regimes.
We study the resolvent for nontrapping obstacles on manifolds with Euclidean ends. It is well known that for such manifolds, the outgoing resolvent satisfies $|chi R(k) chi|_{L^2to L^2}leq C{k}^{-1}$ for ${k}>1$, but the constant $C$ has been little
We establish new results concerning the existence of extremisers for a broad class of smoothing estimates of the form $|psi(| abla|) exp(itphi(| abla|)f |_{L^2(w)} leq C|f|_{L^2}$, where the weight $w$ is radial and depends only on the spatial variab
In this paper we develop an existence theory for the nonlinear initial-boundary value problem with singular diffusion $partial_t u = text{div}(k(x) abla G(u))$, $u|_{t=0}=u_0$ with Neumann boundary conditions $k(x) abla G(u)cdot u = 0$. Here $xin Bs
We prove well-posedness and regularity results for elliptic boundary value problems on certain domains with a smooth set of singular points. Our class of domains contains the class of domains with isolated oscillating conical singularities, and hence