Information Dissemination Problem Research Articles

Why Does Bank Screening Matter? Private Information and Publicly Traded Securities

When bank asset portfolios were first securitized in the 1970s, much attention was paid to making the securitized instruments, such as mortgage-backed securities (MBSs), attractive to what was then a limited number of institutional investors. Following the initial issues, the practice of securitization and demand for securitization instruments both grew strongly throughout the 70s and 80s, and at particularly rapid rates from the 1990s until the crisis of 2007-2008. Since the crisis, demand has fallen off sharply, although at least one new issue of residential mortgage backed securities was reported in April 2012. This paper focuses on a little-recognized but crucial feature of securitization, namely the role of bank information production in determining the quality of securitization instruments. The paper argues both that bank information production is fundamental to determining the quality of securitization instruments, and that the impacts of any changes in information production activity take time for market agents to assess. Moreover, since bank information is produced by assessing individual loan applications, changes in information processing practices can take place rapidly and can also be difficult to detect. The combined result of these features is that information on market-traded securitization instruments can become stale, leading in turn to the possibility of sudden changes in securities valuation as and when information dissemination problems are detected. The paper models the process in order to study the implications in detail. The paper then argues that the skin-in-the game provisions of current Dodd-Frank legislation are too weak to cure information production and transmission problems. On the other hand, a bank-issued put accompanying a securitization issue could go far toward resolving the moral hazard and timing problems affecting the securitization process.

Random walk with jumps in large-scale random geometric graphs

The information dissemination problem in large-scale networking environments like wireless sensor networks and ad hoc networks is studied here considering random geometric graphs and random walk based approaches. A new type of random walk based agent is proposed in this paper and an analytical expression with respect to coverage (i.e., the proportion of the network nodes visited by the random walk agent) as a function of the number of the agent movements is derived. It is observed that the cover time of many of already existing random walk based variants is large in random geometric graphs of low degree (as it is commonly the case is wireless environments). As this inefficiency is attributed (as discussed in the paper) to the inability of existing random walk based solutions to move away from already likely covered areas, a mechanism for directional movement (i.e., jumping) of the random walk based agent is proposed and studied, that allows the agent to jump to different network areas, most likely not covered yet. The proposed mechanism (Jumping Random Walk) is studied analytically and via simulations and the parameters (of the network topology and the mechanism) under which the proposed scheme outperforms existing random walk based variations are determined.

An Algorithm for Multi-Source Broadcasting on Kautz Digraphs Using 2-Cycle Rooted Trees

Multi-source broadcasting is one of the information dissemination problems on interconnection networks such that some (but not all) units disseminate distinct information to all other units. In this paper, we discuss multi-source broadcasting on the Kautz digraph which is one of the models of interconnection networks. We decompose the Kautz digraph K(d, n) into isomorphic cycle-rooted trees whose root-cycle has length 2, then we present an algorithm for multi-source broadcasting using these cycle-rooted trees. This algorithm is able to treat d(d+1) messages simultaneously and takes the same order for required times as lower bound.

Multisource Broadcasting on de Bruijn and Kautz Digraphs Using Isomorphic Factorizations into Cycle-Rooted Trees

Multi-source broadcasting is one of the information dissemination problems on communication networks such that some units disseminate distinct messages to all other units. In this paper, we study multi-source broadcasting on the de Bruijn and Kautz digraphs which are the models of interconnection networks. In [8] and [12], a cycle-rooted tree which has a large root-cycle is constructed by composition of isomorphic factors, and the multi-source broadcasting is executed on the cycle-rooted tree. On the other side, we execute multi-source broadcasting on each isomorphic factors at the same time. We present a method for multi-source broadcasting using isomorphic cycle-rooted trees which factorize these digraphs, and investigate its efficiency.

On broadcasting in unicyclic graphs

Broadcasting is an information dissemination problem in a connected network, in which one node, called the originator, disseminates a message to all other nodes by placing a series of calls along the communication lines of the network. Finding the broadcast time of a vertex in an arbitrary graph is NP-complete. The polynomial time solvability is shown only for trees. In this paper we present a linear algorithm that determines the broadcast time of any originator in an arbitrary unicyclic graph. As a byproduct, we find a broadcast center of the unicyclic graph. We also present an O(|V|+k 2) algorithm to find the broadcast time of an arbitrary unicyclic graph, where k is the length of the cycle. In the last section we give tight lower and upper bounds on broadcast time of a spanning tree based on the broadcast time of the unicyclic graph.

The librarianship and the information science in the Charles Sender Pierce’s science taxonomy

Mostra a taxionomia das ciências desenvolvida por Charles Sanders Peirce (1839-1914) que divide as ciências em três ramos: ciências teóricas, ciências da revisão e ciências aplicadas. Detalha principalmente as ciências teóricas: a Matemática, a Filosofia e a Idioscopia. Discute também o conceito de Biblioteconomia e de Ciência da Informação e que segundo as definições e características, encontradas na literatura consultada, estão na condição de ciências aplicadas, direcionadas a problemas práticos da sociedade, ou seja, o problema de controle e disseminação da informação. Palavras-chave Classificação das ciências; Ciência da informação; Biblioteconomia Abstract It shows the taxonomy of the sciences developed by Charles Sanders Peirce (1839-1914) which divides the science in three branches: theorical sciences, revision science and applied sciences. It details, meanly the theorical sciences: Mathematics, Philosophy and Idioscopy. It discuss also the concept of Librarianship and Information Science, according to definitions and caractheristics that were found in the consulted literature, are in the condition of applied science and directioned to pratical problems of the society, that is the problem of information control and dissemination. Key words Science classification; Information science, Librarianship

Minimum linear gossip graphs and maximal linear (Δ, k)‐gossip graphs

AbstractGossiping is an information dissemination problem in which each node of a communication network has a unique piece of information that must be transmitted to all other nodes using two‐way communications between pairs of nodes along the communication links of the network. In this paper, we study gossiping using a linear‐cost model of communication which includes a start‐up time and a propagation time which is proportional to the amount of information transmitted. A minimum linear gossip graph is a graph (modeling a network), with the minimum possible number of links, in which gossiping can be completed in minimum time under the linear‐cost model. For networks with an even number of nodes, we prove that the structure of minimum linear gossip graphs is independent of the relative values of the start‐up and unit propagation times. We prove that this is not true when the number of nodes is odd. We present four infinite families of minimum linear gossip graphs. We also present minimum linear gossip graphs for all even numbers of nodes n ≤ 32 except n = 22. A linear (Δ, k)‐gossip graph is a graph with maximum degree Δ in which gossiping can be completed in k rounds with minimum propagation time. We present three infinite families of maximal linear (Δ, k)‐gossip graphs, that is, linear (Δ, k)‐gossip graphs with a maximum number of nodes. We show that not all minimum broadcast graphs are maximal linear (Δ, k)‐gossip graphs. © 2001 John Wiley & Sons, Inc.

Concurrent multicast in weighted networks

Concurrent multicast is the problem of information dissemination from a set of source nodes to a set of destination nodes in a network with cost function: Each source node s needs to multicast a block of data B(s) to the set of destinations. We are interested in protocols for this problem which have minimum communication cost. We consider both the usual case in which any transmitted message can consist of an arbitrary number of data blocks and the case in which each message must consist of exactly one block of data. The problem of determining the minimum cost to perform concurrent multicast from a given set of sources to a set of destinations is NP-hard under both assumptions. We give approximation algorithms to efficiently perform concurrent multicast in arbitrary networks. We also analyze the communication time and communication complexity, i.e., the product of the communication cost and time, of our algorithms.

Optimal total exchange in Cayley graphs

Consider an interconnection network and the following situation: Every node needs to send a different message to every other node. This is the total exchange or all-to-all personalized communication problem, one of a number of information dissemination problems known as collective communications. Under the assumption that a node can send and receive only one message at each step (single-port model), it is seen that the minimum time required to solve the problem is governed by the status (or total distance) of the nodes in the network. We present a time-optimal solution for any Cayley network. Rings, hypercubes, cube-connected cycles, and butterflies are some well-known Cayley networks which can take advantage of our method. The solution is based on a class of algorithms which we call node-invariant algorithms and which behave uniformly across the network.

On the structure of minimum broadcast digraphs

Broadcasting is a problem of information dissemination described for a group of individuals connected by a communication network, where one individual has an item of information and needs to communicate it to everyone else. Numerous previous papers have investigated ways to construct sparse undirected graphs (networks) in which this process can be completed in minimum time. In this paper, we consider the broadcast problem in directed graphs. We describe and recall some techniques to construct sparse digraphs on n vertices in which broadcasting can be completed in minimum time. For n=2 p−1 and n=2 p−2 , we show that these techniques produce the sparsest possible digraphs of this type (called minimum broadcast digraphs, or MBDs). In the case n=2 p−1 , we give one class of MBDs, as for the case n=2 p−2 , we give two non isomorphic classes of MBDs. We also show a class of MBDs on n=2 p vertices which is non isomorphic to the one given in Liestman and Peters (Discrete Appl. Math. 37/38 (1992) 401–419). For some other infinite classes of values of n ( n=2 p−1+1, n=2 p−3 and n=2 p−4 ), we also give techniques that produce the best lower and upper bounds on the size of MBDs known so far.

A study of minimum gossip graphs

Gossiping and broadcasting are two problems of information dissemination described in a group of individuals connected by a communication network. In broadcasting, one individual has an item of information and needs to communicate it to everyone else. In gossiping, every person in the network knows a unique item of information and needs to communicate it to everyone else. Those two communication patterns find their main applications in the field of interconnection networks for parallel and distributed architecture. After reviewing some of the main results that have been obtained on these problems, we give new properties concerning gossiping, mainly about the structure of the networks with n nodes gossiping in minimum time and their minimum number, G( n), of communication links. These properties lead to new bounds for G( n) in the general case, and in particular when 1⩽ n⩽32. Moreover, for some values of n (namely n=15,24,28), we show the exact value of G( n).

Neighbourhood information dissemination in the star graph

This paper studies two neighborhood information dissemination problems in the star graph (n-star): The neighborhood broadcast problem (NBP) is the problem of disseminating a message from the source vertex to all the vertices adjacent to the source vertex and the neighborhood gossiping problem (NGP) is the problem of exchanging messages among all neighboring vertices in the given graph. We propose two neighborhood information dissemination schemes in n-star under the single-port, half-duplex model: The first scheme completes a neighborhood broadcast in 1.5 log/sub 2/ n+O(1) time units and the second scheme completes a neighborhood gossiping in 2.88 log/sub 2/ n+o(logn) time units. We also derive a lower bound on the neighborhood gossiping of 2.88 log/sub 2/ n+O(1) time units, which implies that the latter scheme is optimal with respect to the leading term.

ON BROADCASTING TIME

Broadcasting is an information dissemination problem in which a particular node in a network must transmit an item of information to all the other nodes. In this work we present new lower bounds for the time needed to complete this process in arbitrary graphs. In particular we generalize a result of P. Fraigniaud and E. Lazard [Discrete Applied Mathematics, 53 (1994) 79–133] which states that if in a graph there are at least two vertices in distance equal to the diameter from the originator, then broadcasting requires time at least equal to the diameter plus one.

Genetic Programming to Design Communication Algorithms for Parallel Architectures

Broadcasting is an information dissemination problem in which a message originating at one node of a communication network (modeled as a graph) is to be sent to all other nodes as quickly as possible. This paper describes a new way of producing broadcasting schemes using genetic programming. This technique has proven successful by easily finding optimal algorithms for several well-known families of networks (grids, hypercubes and cycle connected cubes) and has indeed generated a new scheme for butterflies that improves the known upper bound for the broadcasting time of these networks.

Strategies for Path-Based Multicasting in Wormhole-Routed Meshes

Multicasting is an information dissemination problem which consists, for a processor of a distributed memory parallel computer, in sending the same message to a subset of processors. In this paper, we propose new multicast algorithms for a mesh network usingwormholerouting with apath-basedfacility. These new algorithms generally perform faster than algorithms previously described in the literature under the same model. We used as the criteria for comparing algorithms theoff-line computation timenecessary to prepare the multicast and thecommunication timerequired to complete the multicast.

Optimized broadcasting and multicasting protocols in cut-through routed networks

This paper addresses the one-to-all broadcasting problem and the one-to-many broadcasting problem, usually simply called broadcasting and multicasting, respectively. Broadcasting is the information dissemination problem in which a node of a network sends the same piece of information to all the other nodes. Multicasting is a partial broadcasting in the sense that only a subset of nodes forms the destination set. Both operations have many applications in parallel and distributed computing. In this paper, we study these problems in both line model, and cut-through model. The former assumes long distance calls between nonneighboring processors. The latter strengthens the line model by taking into account the use of a routing function. Long distance calls are possible in circuit-switched and wormhole-routed networks, and also in many networks supporting optical facilities. In the line model, it is well known that one can compute in polynomial time a [log/sub 2/n]-round broadcast or multicast protocol for any arbitrary network. Unfortunately such a protocol is often inefficient from a practical point of view because it does not use the resources of the network in a balanced way. In this paper, we present a new algorithm to compute broadcast or multicast protocols. This algorithm applies under both line and cut-through models. Moreover, it returns protocols that efficiently use the bandwidth of the network. From a complexity point of view, we also show that most of the optimization problems relative to the maximization of the efficiency of broadcast or multicast protocols in terms of switching time or vertex load are NP-complete. We have, however, derived polynomial efficient solutions for tree-networks.

Capture and Dissemination of Specialized Knowledge in Network Organizations

I present a model for the capture and retrieval of organizational memory that can help overcome the information dissemination problem faced by network organizations. Network organizations are made of small, heterogeneous, product-oriented teams. In these organizations, the specialization of knowledge that has characterized functional hierarchies can be lost as the functional units in which this expertise was created and shared are dismantled. The preservation and dissemination of expert knowledge thus becomes a major issue to be addressed by these organizations, whose competitive advantage depends on this specialization. The problem of capturing project-related organizational memory is addressed with a 3 step solution: (a) the use of explicit work processes; (b) the development of models capable of representing these processes, the artifacts that are developed, and the rationale used during decision making; and (c) the implementation and deployment of computer tools that support the development processes selected and that, in doing so, record and document the project. I address the problem of accessing information from projects developed elsewhere in the organization and propose a solution based on monitoring the user's manipulation of information and creating hypotheses of his or her information needs. These hypotheses are then used as queries by a fuzzy information retrieval engine that produces a ranked list of documents that are suggested to the user as being relevant to his or her information needs. As the user manipulates these documents, the hypothesis is updated, triggering a new retrieval and the update of the list of suggested documents. The feasibility of the approach is demonstrated with the implementation of a prototype.

Cyclic gossiping times for some classes of graphs

Gossiping and broadcasting are two problems of information dissemination described for a group of individuals connected by a communication network. In gossiping, every person in the network knows a unique item of information and needs to communicate it to everyone else. In broadcasting, one individual has an item of information which needs to be communicated to everyone else. A variation of gossiping, called cyclic gossiping, recently introduced by Liestman and Richards, is studied here for certain classes of graphs. © 1996 John Wiley & Sons, Inc.

AIDS Knowledge, Attitudes and Beliefs Among Chinese College Students

With growing numbers of reported HIV cases in The People's Republic of China, PRC health officials face the same information dissemination problems that have plagued other nations for a decade. The purpose of this study was to begin to understand Chinese college students' knowledge, attitudes and beliefs about HIV/AIDS as well as the cultural barriers which may prevent the acceptance of AIDS public service efforts. Focus group interviews were conducted with 76 college students at Xiamen University, PRC. Interviews revealed that many inaccurate beliefs exist regarding the AIDS disease and its modes of transmission. While many of the respondents reported that fate was the determining factor in trans mission of HIV, most felt distanced--physically, morally and culturally--from those at risk.

Minimum gossip bus networks

Gossiping is an information dissemination problem in which each node of a communication network has a unique piece of information that must be transmitted to all the other nodes. A bus network is a network of processing elements that communicate by sending messages along buses in a sequence of calls. We assume that (i) each node can participate in at most one call at a time, (ii) a node can either send or receive on/ from a bus (exclusively), (iii) no more than one node can send a message on a given bus at a given time, and (iv) communicating a message on a bus takes a unit of time. This model extends the telegraph model in allowing the number of nodes connected to each bus to be as large as needed, instead of being bounded by 2. In this paper, we are interested in minimizing the hardware of a bus network in keeping optimal the communication performances for solving the gossiping problem. More precisely, we compute the minimum number of buses required for gossiping to be optimal. Similarly, we give upper bounds on the minimum length of buses required for gossiping to be optimal. Finally, we combine the two approaches in trying to minimize both parameters: length and number of buses.