Compatibility of traces on the edges and corners of a polyhedron

Trace operators of any order can be defined on the edges of a polygon or fa ces of a polyhedron. However compatibility conditions must be enforced on t he corners of the polygon, on the edges and corners of the polyhedron, in o rder that these traces admit a lifting which has optimal regularity. The ai m of this Note is to identify these conditions. (C) 2000 Academie des scien ces/Editions scientifiques et medicales Elsevier SAS.