sentences:  By restating the normal stress formula_76 in terms of the contact pressure, formula_77; i.e., formula_78 the Kuhn-Tucker problem can be restated as in standard complementarity form i.e.formula_79 In the linear elastic case the gap can be formulated as formula_80 where formula_81is the rigid body separation, formula_82 is the geometry/topography of the contact (cylinder and roughness) and formula_83 is the elastic deformation/deflection.If the contacting bodies are approximated as linear elastic half spaces, the Boussinesq-Cerruti integral equation solution can be applied to express the deformation (formula_84) as a function of the contact pressure (formula_77); i.e.,formula_86 where formula_87for line loading of an elastic half space and formula_88 for point loading of an elastic half-space.