Un graphe lini est dit planaire si on peut le dessiner dans le plan saris que les a&es se recoupent. Un probleme bien nature1 et rtsolu par Kuratowski [KI] est de trouver une caracterisation des graphes planaires. On pourra ausi a ce sujet consulter les monographies [BE, WE, TE] . 11 se trouve que les mtthodes developpees dans nos articles precedents [C-C, [CV,], G ig4] permettent d’exhiber un ...

this paper introduces an implicit scheme for a   continuous representation of nonexpansive mappings on a closed convex subset of a hilbert space with respect to a   sequence of invariant means defined on an appropriate space of bounded, continuous real valued functions of the semigroup.   the main result is to    prove the strong convergence of the proposed implicit scheme to the unique solutio...

Let Φ : M −→ g be a proper moment map associated to an action of a compact connected Lie group, G, on a connected symplectic manifold, (M, ω). A collective function is a pullback via Φ of a smooth function on g∗. In this paper we present four new results about the relationship between the collective functions and the G-invariant functions in the Poisson algebra of smooth functions on M . More s...