Multiplier spaces for the mortar finite element method in three dimensions

We consider the construction of multiplier spaces for use with the mortar f inite element method in three spatial dimensions on globally or locally qua si-uniform meshes. A set of abstract conditions is given for the multiplier spaces which are sufficient to guarantee a stable and convergent mortar ap proximation. Three examples of multipliers satisfying these conditions are presented. The rst one is a dual basis example, while the remaining two are based on finite volumes. Finally, the results of computational examples il lustrating the theory are reported.