THREE APPLICATIONS OF TRANSACTION COST ECONOMICS IN ROMANIA

We begin by investigating the use of complex contracts in Romania. A transparent transaction cost economics (TCE) model generates the hypothesis that buyer and seller relationship-specific investments have opposite effects on contract complexity. Our analysis counters the problem of unobserved heterogeneity, generates estimates of the effects of specific investments that are opposite in sign on opposite sides of the agreement, and explains the patterns in the biases of ordinary least-squares estimates. We continue by presenting a simple methodology for measuring transaction costs at agreement level. These costs are assessed as large, accounting for more than a fifth of value added. The validity of the measure is tested and quality of the data is analyzed. Finally, we investigate the determinants of transaction costs estimates thus obtained. Results show that TCE theory is very successful at predicting the existence of transaction costs and moderately so at predicting their size when incurred by firms.new institutional economics, transaction cost economics, contract complexity

THREE APPLICATIONS OF TRANSACTION COST ECONOMICS IN ROMANIA

International Monetary Fund Institute, 700 19th Street, N.W,.Washington, D.C. 20431application, transaction

On the Borda Method for Multicriterial Decision-Making

The present paper discusses two issues with multicriterial decision-making methods of Borda type (when scores such as n, n-1,…, 2, 1 are given to the objects to be ranked and the hierarchy is obtained based on the totals of these scores). The first issue is related to the influence on the result of various transformations of the scores. We show that a linear transformation of the scores does not change the final ranking and that (almost) any polynomial of second degree or more, with positive coefficients, can alter the solution (ranking). The same happens if one changes the scores by employing the logarithm, exponential, or square root functions. In the second part of the paper we consider an iterated version of the Borda method. We show that this method is not robust: there are cases when different solutions are returned at different iterations.borda method

Computing with cells: membrane systems - some complexity issues.

Membrane computing is a branch of natural computing which abstracts computing models from the structure and the functioning of the living cell. The main ingredients of membrane systems, called P systems, are (i) the membrane structure, which consists of a hierarchical arrangements of membranes which delimit compartments where (ii) multisets of symbols, called objects, evolve according to (iii) sets of rules which are localised and associated with compartments. By using the rules in a nondeterministic/deterministic maximally parallel manner, transitions between the system configurations can be obtained. A sequence of transitions is a computation of how the system is evolving. Various ways of controlling the transfer of objects from one membrane to another and applying the rules, as well as possibilities to dissolve, divide or create membranes have been studied. Membrane systems have a great potential for implementing massively concurrent systems in an efficient way that would allow us to solve currently intractable problems once future biotechnology gives way to a practical bio-realization. In this paper we survey some interesting and fundamental complexity issues such as universality vs. nonuniversality, determinism vs. nondeterminism, membrane and alphabet size hierarchies, characterizations of context-sensitive languages and other language classes and various notions of parallelism

Decision P Systems and the P =NP Conjecture

We introduce decision P systems, which are a class of P systems with symbol-objects and external output. The main result of the paper is the following: if there exists an NP–complete problem that cannot be solved in polynomial time, with respect to the input length, by a deterministic decision P system constructed in polynomial time, then P = NP. From Zandron-Ferreti-Mauri’s theorem it follows that if P = NP, then no NP–complete problem can be solved in polynomial time, with respect to the input length, by a deterministic P system with active membranes but without membrane division, constructed in polynomial time from the input. Together, these results give a characterization of P = NP in terms of deterministic P systems

Counting Membrane Systems

A decision problem is one that has a yes/no answer, while a counting problem asks how many possible solutions exist associated with each instance. Every decision problem X has associated a counting problem, denoted by #X, in a natural way by replacing the question “is there a solution?” with “how many solutions are there?”. Counting problems are very attractive from a computational complexity point of view: if X is an NP-complete problem then the counting version #X is NP-hard, but the counting version of some problems in class P can also be NP-hard. In this paper, a new class of membrane systems is presented in order to provide a natural framework to solve counting problems. The class is inspired by a special kind of non-deterministic Turing machines, called counting Turing machines, introduced by L. Valiant. A polynomial-time and uniform solution to the counting version of the SAT problem (a well-known #P-complete problem) is also provided, by using a family of counting polarizationless P systems with active membranes, without dissolution rules and division rules for non-elementary membranes but where only very restrictive cooperation (minimal cooperation and minimal production) in object evolution rules is allowed

Drip and Mate Operations Acting in Test Tube Systems and Tissue-like P systems

The operations drip and mate considered in (mem)brane computing resemble the operations cut and recombination well known from DNA computing. We here consider sets of vesicles with multisets of objects on their outside membrane interacting by drip and mate in two different setups: in test tube systems, the vesicles may pass from one tube to another one provided they fulfill specific constraints; in tissue-like P systems, the vesicles are immediately passed to specified cells after having undergone a drip or mate operation. In both variants, computational completeness can be obtained, yet with different constraints for the drip and mate operations

A linear-time tissue P system based solution for the 3-coloring problem

In the literature, several examples of the efficiency of cell-like P systems regarding the solution of NPcomplete problems in polynomial time can be found (obviously, trading space for time). Recently, different new models of tissue-like P systems have received important attention from the scientific community. In this paper we present a linear-time solution to an NP-complete problem from graph theory, the 3–coloring problem, and we discuss the suitability of tissue-like P systems as a framework to address the efficient solution to intractable problems.Ministerio de Educación y Ciencia TIN2005-09345-C04-01Junta de Andalucía TIC-58

Segmentation in 2D and 3D image using Tissue-Like P System

Membrane Computing is a biologically inspired computational model. Its devices are called P systems and they perform computations by applying a finite set of rules in a synchronous, maximally parallel way. In this paper, we open a new research line: P systems are used in Computational Topology within the context of the Digital Image. We choose for this a variant of P systems, called tissue-like P systems, to obtain in a general maximally parallel manner the segmentation of 2D and 3D images in a constant number of steps. Finally, we use a software called Tissue Simulator to check these systems with some examples

A uniform family of tissue P systems with cell division solving 3-COL in a linear time

Several examples of the efficiency of cell-like P systems regarding the solution of NPcomplete problems in polynomial time can be found in the literature(obviously, trading space for time). Recently, different new models of tissue-like P systems have received much attention from the scientific community. In this paper we present a linear-time solution to an NP-complete problem from graph theory, the 3-coloring problem, and we discuss the suitability of tissue-like P systems as a framework to address the efficient solution to intractable problems.Ministerio de Educación y Ciencia TIN2005-09345-C04-01Junta de Andalucía TIC-58