We prove weak and strong maximum principles, including a Hopf lemma, for classical solutions to equations defined by linear, second-order, partial differential operators with non-negative characteristic form (degenerate-elliptic operators), in the presence of a second-order boundarycondition of Ventcel type along the degeneracy locus of the principle symbol of the operator on the domain boundary. We apply these maximum principles to obtain uniqueness and a priori maximum principle estimates for classical solutions to boundary value and obstacle problems defined by these degenerate-elliptic operators , again in the presence of a second-order boundary condition, for Dirichlet or Neumann boundary conditions along the complement of the degeneracy locus. We also prove weak maximum principles and uniqueness for solutions to the corresponding variational equations and inequalities defined with the aide of weighted Sobolev spaces. The domain is allowed to be unbounded when the operator coefficients and solutions obey certain growth conditions.
We prove weak and strong maximum principles, including a Hopf lemma, for smooth subsolutions to equations defined by linear, second-order, partial differential operators whose principal symbols vanish along a portion of the domain boundary. The boundary regularity property of the smooth subsolutions along this boundary vanishing locus ensures that these maximum principles hold irrespective of the sign of the Fichera function. Boundary conditions need only be prescribed on the complement in the domain boundary of the principal symbol vanishing locus. We obtain uniqueness and a priori maximum principle estimates for smooth solutions to boundary value and obstacle problems defined by these boundary-degenerate elliptic operators for partial Dirichlet or Neumann boundary conditions along the complement of the boundary vanishing locus. We also prove weak maximum principles and uniqueness for solutions to the corresponding variational equations and inequalities defined with the aide of weighted Sobolev spaces. The domain is allowed to be unbounded when the operator coefficients and solutions obey certain growth conditions.
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classical solutions
smooth subsolutions
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with non-negative characteristic form (degenerate-elliptic operators), in the presence of a second-order boundarycondition of Ventcel type along the degeneracy locus of
whose principal symbols vanish along a portion of the domain boundary. The boundary regularity property of
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principle symbol of the operator on the domain boundary. We apply these maximum principles to
smooth subsolutions along this boundary vanishing locus ensures that these maximum principles hold irrespective of the sign of the Fichera function. Boundary conditions need only be prescribed on the complement in the domain boundary of the principal symbol vanishing locus. We
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classical
smooth
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degenerate-elliptic operators , again in the presence of a second-order boundary condition, for
boundary-degenerate elliptic operators for partial
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degeneracy
boundary vanishing