In this paper, we show that the correspondence discovered by Koshevoy (1999) and, Johnson and Dean (1998) between anti-exchange closure operators and path independent choice operators is a duality between two semilattices of such operators. Then we use this duality to obtain old and new results...

We build spaces of q.p. (quasi-periodic) functions and we establich some of their properties. They are motivated by the Perceival approach to q.p. solutions of Hamiltonian systems. The periodic solutions of an adequat Partial Differential Equation are related to the q.p. solutions of an Ordinar...

The purpose of this paper is to provide a characterization result for the canonical basis of an arbitrary closure operator. This theorem strengthens the result of Burosch, Demetrovics and Katona, who propose in [1] a characterization of the generating system of a closure operator defined by the...

We present and prove the equality between the core and the set of Walras allocations for a pure exchange economy with l goods and a continuum of consumers, represented by an atomless measure space.

We devise an approximation-preserving reduction of expansion O between weighted and unweighted versions of a class of problems called weighted hereditary induced-subgraph maximisation problems. This allows us to perform a first improvement of the best approximation ratio for the weighted...

In order to get rid of the condition X=Y, we introduce an extension of the Dynkin game by allowing for an extended set of strategies, namely the set of mixed strategies. The main result of the paper is that the extended Dynkin game has a value when the processes X and Y are only restricted to be...

We shape a formal framework for distinguishing the behaviour of constructive and non-constructive polynomial time approximation algorithms for NP optimization problems. We introduce a new class, called SubNPO, that includes NPO and also some other problems used in recent works.

In discrete three-dimensional dynamical systems frequently encountered in dynamic general equilibrium models, local indeterminacy -sunspot equilibria - and local bifurcations -endogenous deterministic fluctuations - issues are quite difficult to handle. Pitfalls derive from the fact that in...

The standard equivalence result on core and Walras equilibrium allocations uses a non-satiation and an interiority assumption. Konovalov introduced the rejective core for exchange economies with possibly satiated preferences and proved that there, the fuzzy rejective core coincides with the set...

We draw a rough shape of a general formal framework for polynomial approximation theory which encompasses the existing one by allowing the expression of new types of results. We show how this framework incorporates all the existing approximation results and, moreover, how new types of results...