Sistem Himpunan Korum dan Masalah Resolusi Konflik Terdistribusi

The aims of this study are (1) to analyze relaxation of the characteristics of distributed mutual exclusion problem of various problems of widening conflict resolution in distributed system, (2) to develop coterie set system in solving any types of conflict resolution in distributed system, (3) to analyze coterie set to solve the distributed conflict problem. The method used was literary study by collecting research materials through library journals that relevant with the subject matter i.e. quorum set system and various problems of distributed conflict resolution. The results of the research indicated that mutual exclusion (mutex) can be solved with coterie, k-mutex problem can be solved by using k-coterie, read-writer problem can be solved by using bicoteri, restricted resources problem can be solved by using (m,h,ki)-coterie. For restricted and various resources matter can be constructed with disjoint and simple uniform (m,h,k)-coterie

Theory of anyon excitons: Relation to excitons of nu=1/3 and nu=2/3 incompressible liquids

Elementary excitations of incompressible quantum liquids (IQL's) are anyons, i.e., quasiparticles carrying fractional charges and obeying fractional statistics. To find out how the properties of these quasiparticles manifest themselves in the optical spectra, we have developed the anyon exciton model (AEM) and compared the results with the finite-size data for excitons of nu=1/3 and nu=2/3 IQL's. The model considers an exciton as a neutral composite consisting of three quasielectrons and a single hole. The AEM works well when the separation between electron and hole confinement planes, h, is larger than the magnetic length l. In the framework of the AEM an exciton possesses momentum k and two internal quantum numbers, one of which can be chosen as the angular momentum, L, of the k=0 state. Existence of the internal degrees of freedom results in the multiple branch energy spectrum, crater-like electron density shape and 120 degrees density correlations for k=0 excitons, and the splitting of the electron shell into bunches for non-zero k excitons. For h larger than 2l the bottom states obey the superselection rule L=3m (m are integers starting from 2), all of them are hard core states. For h nearly 2l there is one-to-one correspondence between the low-energy spectra found for the AEM and the many- electron exciton spectra of the nu=2/3 IQL, whereas some states are absent from the many-electron spectra of the nu=1/3 IQL. We argue that this striking difference in the spectra originates from the different populational statistics of the quasielectrons of charge conjugate IQL's and show that the proper account of the statistical requirements eliminates excessive states from the spectrum. Apparently, this phenomenon is the first manifestation of the exclusion statistics in the anyon bound states.Comment: 26 pages with 9 figures, typos correcte

Distributed mutual exclusion algorithms

In this thesis we present three original algorithms which solve the distributed mutual exclusion problem. Two of the three solve the problem of allowing only one site at a time into the critical section. The third solves the more difficult problem of allowing a specific number of sites (k sites) into the critical section at a time; All three algorithms are Token Based . That is, they make use of a token and token queue in order to guarantee mutual exclusion. Only the site that currently has the token is allowed to enter its critical section in the 1 mutual exclusion algorithms. Only the sites that have seen the token, since they requested it, are allowed to enter their critical sections in the k mutual exclusion algorithm; The primary goal of our algorithms is efficiency. Both of our 1 mutual exclusion algorithms require between 2 and n messages per critical section (n being the number of sites) depending on the number of requests for the critical section. Our k mutual exclusion has similar requirements between 3 and n messages per critical section depending on the number of requests for the critical section. (Abstract shortened by UMI.)

An asynchronous message-passing distributed algorithm for the global critical section problem

This paper considers the global $(l,k)$-CS problem which is the problem of controlling the system in such a way that, at least $l$ and at most $k$ processes must be in the CS at a time in the network. In this paper, a distributed solution is proposed in the asynchronous message-passing model. Our solution is a versatile composition method of algorithms for $l$-mutual inclusion and $k$-mutual exclusion. Its message complexity is $O(|Q|)$, where $|Q|$ is the maximum size for the quorum of a coterie used by the algorithm, which is typically $|Q| = \sqrt{n}$.Comment: This is a modified version of the conference paper in PDAA201

Exclusion and Object Tracking in a Network of Processes

This paper concerns two fundamental problems in distributed computing---mutual exclusion and mobile object tracking. For a variant of the mutual exclusion problem where the network topology is taken into account, all existing distributed solutions make use of tokens. It turns out that these token-based solutions for mutual exclusion can also be adapted for object tracking, as the token behaves very much like a mobile object. To handle objects with replication, we go further to consider the more general $k$-exclusion problem which has not been as well studied in a network setting. A strong fairness property for $k$-exclusion requires that a process trying to enter the critical section will eventually succeed even if \emph{up to} $k-1$ processes stay in the critical section indefinitely. We present a comparative survey of existing token-based mutual exclusion algorithms, which have provided much inspiration for later $k$-exclusion algorithms. We then propose two solutions to the $k$-exclusion problem, the second of which meets the strong fairness requirement. Fault-tolerance issues are also discussed along with the suggestion of a third algorithm that is also strongly fair. Performances of the three algorithms are compared by simulation. Finally, we show how the various exclusion algorithms can be adapted for tracking mobile objects

Dynamic sharing of a multiple access channel

In this paper we consider the mutual exclusion problem on a multiple access channel. Mutual exclusion is one of the fundamental problems in distributed computing. In the classic version of this problem, n processes perform a concurrent program which occasionally triggers some of them to use shared resources, such as memory, communication channel, device, etc. The goal is to design a distributed algorithm to control entries and exits to/from the shared resource in such a way that in any time there is at most one process accessing it. We consider both the classic and a slightly weaker version of mutual exclusion, called ep-mutual-exclusion, where for each period of a process staying in the critical section the probability that there is some other process in the critical section is at most ep. We show that there are channel settings, where the classic mutual exclusion is not feasible even for randomized algorithms, while ep-mutual-exclusion is. In more relaxed channel settings, we prove an exponential gap between the makespan complexity of the classic mutual exclusion problem and its weaker ep-exclusion version. We also show how to guarantee fairness of mutual exclusion algorithms, i.e., that each process that wants to enter the critical section will eventually succeed