__Abstract__:
**Sous les facettes des Polyèdres, sous les facettes, les polyèdres**

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In this survey we describe some results on combinatorial polyhedra and
their applications in optimization. We begin by recalling the Simplex
method, then we give some elementary properties of polyhedra,
particularly
the Weyl theorem. We thus introduce the combinatorial polyhedra, we
give the characterization of the convex hull of the independant subsets
common to two matroids on the same set. We thus give the description of
the classical approximation of the travelling salesman polyhedron. We
thus describe some interior point methods, and deduce, in one
important practical case, the polynomial equivalence between
separation and optimization on polyhedra. We end this survey noting
some other points of view on combinatorial optimization.
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