A heuristic for broadcasting in arbitrary networks

Finding the optimal broadcasting schedule in an arbitrary network is an NP-hard problem. Many papers have been published on the topic of finding an efficient and effective heuristic for broadcasting. In this thesis, a heuristic algorithm for broadcasting in arbitrary networks is presented. This heuristic is first tested in several commonly used graphs; such as Butterfly, CCC d , deBruijn and Shuffle Exchange . In these graphs, this heuristic generates almost the same broadcast schedules as the best existing heuristic for broadcasting. However, the time complexity of this heuristic is much lower. The heuristic is also tested in three of the best-known network design models, and the heuristic outperforms the best existing heuristic in these models. The time complexity of this heuristic is O ( R · m ), where R represents the rounds of broadcasting, and m stands for the total number of communication links in the network

A powerful heuristic for telephone gossiping

A refined heuristic for computing schedules for gossiping in the telephone model is presented. The heuristic is fast: for a network with n nodes and m edges, requiring R rounds for gossiping, the running time is O(R n log(n) m) for all tested classes of graphs. This moderate time consumption allows to compute gossiping schedules for networks with more than 10,000 PUs and 100,000 connections. The heuristic is good: in practice the computed schedules never exceed the optimum by more than a few rounds. The heuristic is versatile: it can also be used for broadcasting and more general information dispersion patterns. It can handle both the unit-cost and the linear-cost model. Actually, the heuristic is so good, that for CCC, shuffle-exchange, butterfly de Bruijn, star and pancake networks the constructed gossiping schedules are better than the best theoretically derived ones. For example, for gossiping on a shuffle-exchange network with 2^{13} PUs, the former upper bound was 49 rounds, while our heuristic finds a schedule requiring 31 rounds. Also for broadcasting the heuristic improves on many formerly known results. A second heuristic, works even better for CCC, butterfly, star and pancake networks. For example, with this heuristic we found that gossiping on a pancake network with 7! PUs can be performed in 15 rounds, 2 fewer than achieved by the best theoretical construction. This second heuristic is less versatile than the first, but by refined search techniques it can tackle even larger problems, the main limitation being the storage capacity. Another advantage is that the constructed schedules can be represented concisely

Universal and Robust Distributed Network Codes

Random linear network codes can be designed and implemented in a distributed manner, with low computational complexity. However, these codes are classically implemented over finite fields whose size depends on some global network parameters (size of the network, the number of sinks) that may not be known prior to code design. Also, if new nodes join the entire network code may have to be redesigned. In this work, we present the first universal and robust distributed linear network coding schemes. Our schemes are universal since they are independent of all network parameters. They are robust since if nodes join or leave, the remaining nodes do not need to change their coding operations and the receivers can still decode. They are distributed since nodes need only have topological information about the part of the network upstream of them, which can be naturally streamed as part of the communication protocol. We present both probabilistic and deterministic schemes that are all asymptotically rate-optimal in the coding block-length, and have guarantees of correctness. Our probabilistic designs are computationally efficient, with order-optimal complexity. Our deterministic designs guarantee zero error decoding, albeit via codes with high computational complexity in general. Our coding schemes are based on network codes over ``scalable fields". Instead of choosing coding coefficients from one field at every node, each node uses linear coding operations over an ``effective field-size" that depends on the node's distance from the source node. The analysis of our schemes requires technical tools that may be of independent interest. In particular, we generalize the Schwartz-Zippel lemma by proving a non-uniform version, wherein variables are chosen from sets of possibly different sizes. We also provide a novel robust distributed algorithm to assign unique IDs to network nodes.Comment: 12 pages, 7 figures, 1 table, under submission to INFOCOM 201

Parameterized Verification of Safety Properties in Ad Hoc Network Protocols

We summarize the main results proved in recent work on the parameterized verification of safety properties for ad hoc network protocols. We consider a model in which the communication topology of a network is represented as a graph. Nodes represent states of individual processes. Adjacent nodes represent single-hop neighbors. Processes are finite state automata that communicate via selective broadcast messages. Reception of a broadcast is restricted to single-hop neighbors. For this model we consider a decision problem that can be expressed as the verification of the existence of an initial topology in which the execution of the protocol can lead to a configuration with at least one node in a certain state. The decision problem is parametric both on the size and on the form of the communication topology of the initial configurations. We draw a complete picture of the decidability and complexity boundaries of this problem according to various assumptions on the possible topologies.Comment: In Proceedings PACO 2011, arXiv:1108.145

Miss Olympic Athlete? A Content Analysis of NBC’s Primetime Interviews During the 2016 Summer Olympic Games

The 2016 Summer Olympic Games in Rio de Janeiro has further exposed the difference in sports reporting between sexes. Creating social media controversy, viewers called out the sexist commentary directed towards women athletes emphasizing their relationship status, how many children they have, and male athlete accomplishments over the female’s athletic ability. This content analysis will dive deeper into NBC’s prime-time coverage of the twenty-third Olympiad, examining the sport and non-sport questions brought up during interviews with the male and female athletes. With reporters possessing more control over what is discussed on-air, when compared to live commentators, the goal of this analysis is to examine if a significant difference of sport-related themes remains between sexes, or if a few outliers are drawing disproportionate attention. No significant difference was found between questions asked during interviews with male and female athletes, however, there was a significant difference found between the mean number of non-sport questions posed by male reporters when compared to female reporters. Suggestions for future research are also explored