Although initially originated as a totally empirical relationship to explain the volume of trade between two partners, gravity equation has been the focus of several theoretic models that try to explain it. Specialization models are of great importance in providing a solid theoretic ground for gravity equation in bilateral trade. Some research papers try to improve specialization models by addi...

When does efficiency in the household imply specialization? For example, if we recognize two sectors, “market” and “household,” when does efficiency imply that one spouse specializes in the market and the other in the household? If efficiency did imply specialization, then egalitarian marriages would be inefficient and an equity-efficiency tradeoff inescapable. This paper clarifies the roles th...

This paper proposes a perfect foresight model of a two-region two-sector economy, where localized externalities in the acquisition of skills cause specialization and uneven regional development. The introduction of a new technology either reinforces or reverses this development pattern. Wealth differences are reinforced if, in spite of higher wages, the new technology locates in the advanced re...

We explore a small-open economy with overlapping generations to understand what is the determinant of trade pattern in the dynamic trade theory. In the representative agent model (Baxter (1992) ), even if there are two goods and two production factors, opening up to trade leads to perfect specialization. Using the overlapping generations model, we find that the heterogeneity of the economic age...

Roussel and Rubio proved a lemma which is essential in the proof of the Strong Perfect Graph Theorem. We give a new short proof of the main case of this lemma. In this note, we also give a short proof of Hayward’s decomposition theorem for weakly chordal graphs, relying on a Roussel–Rubio-type lemma. We recall how Roussel–Rubio-type lemmas yield very short proofs of the existence of even pairs ...

We will extend Reed's Semi-Strong Perfect Graph Theorem by proving that unbreakable C 5-free graphs diierent from a C 6 and its complement have unique P 4-structure.

The Wonderful Lemma, that was first proved by Roussel and Rubio, is one of the most important tools in the proof of the Strong Perfect Graph Theorem. Here we give a short proof of this lemma.

We propose a program specialization technique for locally stratified CLP(Z) programs, that is, logic programs with linear constraints over the set Z of the integer numbers. For reasons of efficiency our technique makes use of a relaxation from integers to reals. We reformulate the familiar unfold/fold transformation rules for CLP programs so that: (i) the applicability conditions of the rules a...

A perfect-competition model is developed to analyze duality in specialization and technology such as in the men’s clothing industry, an industry with highly seasonal nature of the business cycle. We show that when the market fluctuation is large enough, some firms will specialize in one good with the advantage of static efficiency, while other firms will generalize in multi-variety production a...