411 research outputs found
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,âŠ, 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 NPâcomplete 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-Mauriâs theorem it follows that if P =
NP, then no NPâcomplete 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
âis there a solution?â with âhow many solutions are there?â. 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 3âcoloring
problem, and we discuss the suitability of tissue-like P systems as a framework to address the efficient
solution to intractable problems.Ministerio de EducaciĂłn y Ciencia TIN2005-09345-C04-01Junta de AndalucĂa 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 EducaciĂłn y Ciencia TIN2005-09345-C04-01Junta de AndalucĂa TIC-58
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