There exist different schemes of model reduction for parametric ordinary differential systems arising from chemical reaction systems. In this paper, we focus on some schemes which rely on quasi-steady states approximations. We show that these schemes can be formulated by means of differential and algebraic elimination. Our formulation is simpler than the classical ones. It permitted us to obtai...

It is well known that the non-spiraling leaves of real analytic foliations of codimension 1 all belong to the same o-minimal structure. Naturally, the question arises of whether the same statement is true for non-oscillating trajectories of real analytic vector fields. We show, under certain assumptions, that such a trajectory generates an o-minimal and model-complete structure together with th...

Let X be a minuscule Schubert variety. In this article, we use the combinatorics of quivers to define new quasi-resolutions of X . We describe in particular all relative minimal models π̂ : X̂ → X of X and prove that all the morphisms π̂ are small (in the sense of intersection cohomology). In particular, all small resolutions of X are given by the smooth relative minimal models X̂ and we describe a...

We prove that every polarity of PG(2k − 1, q), where k ≥ 2, gives rise to a design with the same parameters and the same intersection numbers as, but not isomorphic to PGk(2k, q). In particular, the case k = 2 yields a new family of quasi-symmetric designs. We also show that our construction provides an infinite family of counterexamples to Hamada’s conjecture, for any field of prime order p. P...

Current privacy preserving methods in data publishing always remove the individually identifying attribute first and then generalize the quasi-identifier attributes. They cannot take the individually identifying attribute into account. In fact, tuples will become vulnerable in the situation of multiple tuples per individual. In this paper, we analyze the individually identifying attribute in th...

Some curvature estimates are derived from geometrical data concerning quasi-conformality properties of some commuting linearly independent vector fields on a compact Riemannian manifold.

Clonal growth allows plants to spread horizontally and to experience different levels of resources. If ramets remain physiologically integrated, clonal plants can reciprocally translocate resources between ramets in heterogeneous environments. But little is known about the interaction between benefits of clonal integration and patterns of resource heterogeneity in different patches, i.e., coinc...

We introduce here a new approach to the study of m-quasi-invariants. This approach consists in representing m-quasi-invariants as N tuples of invariants. Then conditions are sought which characterize such N tuples. We study here the case of S3 m-quasi-invariants. This leads to an interesting free module of triplets of polynomials in the elementary symmetric functions e1, e2, e3 which explains c...

It is proved that any non-normable Fréchet space with a semisymmetric absolute basis is isomorphic to the space ω of all scalar sequences. A similar result is shown for quasi-homogeneous absolute bases. It is also proved that any nuclear Fréchet space with a semi-subsymmetric basis is isomorphic to ω.

In this paper we address the problem of a-migrativity (for a fixed a) for semicopulas, copulas and quasi-copulas. We introduce the concept of an a-sum of semicopulas. This new concept allows us to completely characterize a-migrative semicopulas and copulas. Moreover, a-sums also provide a means to obtain a partial characterization of a-migrative quasicopulas. 2010 Elsevier Inc. All rights reser...