An Inverse Method for Policy-Iteration Based Algorithms

We present an extension of two policy-iteration based algorithms on weighted graphs (viz., Markov Decision Problems and Max-Plus Algebras). This extension allows us to solve the following inverse problem: considering the weights of the graph to be unknown constants or parameters, we suppose that a reference instantiation of those weights is given, and we aim at computing a constraint on the parameters under which an optimal policy for the reference instantiation is still optimal. The original algorithm is thus guaranteed to behave well around the reference instantiation, which provides us with some criteria of robustness. We present an application of both methods to simple examples. A prototype implementation has been done

Using Strategy Improvement to Stay Alive

We design a novel algorithm for solving Mean-Payoff Games (MPGs). Besides solving an MPG in the usual sense, our algorithm computes more information about the game, information that is important with respect to applications. The weights of the edges of an MPG can be thought of as a gained/consumed energy -- depending on the sign. For each vertex, our algorithm computes the minimum amount of initial energy that is sufficient for player Max to ensure that in a play starting from the vertex, the energy level never goes below zero. Our algorithm is not the first algorithm that computes the minimum sufficient initial energies, but according to our experimental study it is the fastest algorithm that computes them. The reason is that it utilizes the strategy improvement technique which is very efficient in practice

The level set method for the two-sided eigenproblem

We consider the max-plus analogue of the eigenproblem for matrix pencils Ax=lambda Bx. We show that the spectrum of (A,B) (i.e., the set of possible values of lambda), which is a finite union of intervals, can be computed in pseudo-polynomial number of operations, by a (pseudo-polynomial) number of calls to an oracle that computes the value of a mean payoff game. The proof relies on the introduction of a spectral function, which we interpret in terms of the least Chebyshev distance between Ax and lambda Bx. The spectrum is obtained as the zero level set of this function.Comment: 34 pages, 4 figures. Changes with respect to the previous version: we explain relation to mean-payoff games and discrete event systems, and show that the reconstruction of spectrum is pseudopolynomia

Diastereo- and Enantioselective Pd(II)-Catalyzed Additions of 2-Alkylazaarenes to N-Boc Imines and Nitroalkenes

A chiral Pd(II)–bis(oxazoline) complex was found to be highly effective in promoting the first direct diastereo- and enantioselective addition of alkylazaarenes to N-Boc aldimines and nitroalkenes under mild conditions. Deprotection of Boc-protected products proceeded readily to provide amines in high yields

Multiplication végétative de l'épicéa commun (2ème tranche)

Research projects conducted on the vegetative propagation of the common spruce started in 1981. In 1990, an experiment was initiated in Barres and a pilot-production in Peyrat-le-Château. The experiment confirmed the interest of pure bark as cutting substrate and the uselessness of hormones. On the other hand, the elimination of basal needles did not improve rooting. Finally, the planting of cuttings in December or January instead of March gave better results. The pilot-production with maintenance of the clonal identity and floor heating has been compared to that of the previous two years. The results confirm the fact that rooting was highly dependent on the clones. Therefore, the INRA did not select certain clones which were vigorous and gave a good quality wood. / L'opération de recherches sur la multiplication végétative de l'Epicea commun a débuté en 1981. En 1990, ont été installées une expérimentation aux Barres et une production pilote à Peyrat-le-Château. L'expérimentation a confirmé l'intérêt de l'écorce pure utilisée comme substrat de bouturage, et l'inutilité de l'hormonage. D'autre part, la suppression des aiguilles basales des boutures, dit blessure, n'apporte pas de gain d'enracinement. Enfin, l'installation des boutures en décembre ou janvier donne de meilleurs résultats, qu'en mars. La production pilote, avec conservation de l'identité clonale et chauffage de fond, a été comparée à celle des 2 années précédentes. Elle confirme que les différences d'aptitude clonale à l'enracinement sont très fortes, ce qui condamnera certains clones sélectionnés par l'INRA qui donnaient par ailleurs satisfaction sur la qualité du bois et la vigueur

Wood-Sourced Polymers as Support for Catalysis by Group 10 Transition Metals

Despite providing interesting solutions to reduce the number of synthetic steps, to decrease energy consumption or to generate less waste, therefore contributing to a more sustainable way of producing important chemicals, the expansion of the use of homogeneous catalysis in industrial processes is hampered by several drawbacks. One of the most important is the difficulty to recycle the noble metals generating potential high costs and pollution of the synthesized products by metal traces detrimental to their applications. Supporting the metals on abundant and cheap biosourced polymers has recently appeared as an almost ideal solution: They are much easier to recover from the reaction medium and usually maintain high catalytic activity. The present bibliographical review focuses on the development of catalysts based on group 10 transition metals (nickel, palladium, platinum) supported on biopolymers obtained from wood, such as cellulose, hemicellulose, lignin, and their derivatives. The applications of these catalysts in organic synthesis or depollution are also addressed in this review with examples of C-C couplings, oxidation, or hydrogenation reactions

Organic Nanoparticles as Anticancer and Theranostic Devices

International audienc

Benzylic-type couplings provide an important asymmetric entry to functionalized, non-racemic helicenes

International audienc