  We revisit stress problems in linear elasticity to provide a perspective from
the geometrical and functionalanalytic points of view. For the static stress
problem of linear elasticity with mixed boundary conditions we write the
associated pair of unbounded adjoint operators. The stress solution is found as
an intersection of affine translations of the fundamental subspaces of the
adjoint operators. In particular, we treat the equilibrium equation in the
operator form, involving spaces of traces on a part of the boundary, known as
Lions-Magenes spaces. Our analysis of the pair of adjoint operators for the
problem with mixed boundary conditions relies on the properties of the
analogous pair of operators for the problem with the displacement boundary
conditions, which we also include in the paper.
