Believed belief: science/religion versus Sukuma magic

status: publishe

On the Complexity of Bounded Context Switching

Bounded context switching (BCS) is an under-approximate method for finding violations to safety properties in shared-memory concurrent programs. Technically, BCS is a reachability problem that is known to be NP-complete. Our contribution is a parameterized analysis of BCS. The first result is an algorithm that solves BCS when parameterized by the number of context switches (cs) and the size of the memory (m) in O*(m^(cs)2^(cs)). This is achieved by creating instances of the easier problem Shuff which we solve via fast subset convolution. We also present a lower bound for BCS of the form m^o(cs / log(cs)), based on the exponential time hypothesis. Interestingly, the gap is closely related to a conjecture that has been open since FOCS\u2707. Further, we prove that BCS admits no polynomial kernel. Next, we introduce a measure, called scheduling dimension, that captures the complexity of schedules. We study BCS parameterized by the scheduling dimension (sdim) and show that it can be solved in O*((2m)^(4sdim)4^t), where t is the number of threads. We consider variants of the problem for which we obtain (matching) upper and lower bounds

Run Time Approximation of Non-blocking Service Rates for Streaming Systems

Stream processing is a compute paradigm that promises safe and efficient parallelism. Modern big-data problems are often well suited for stream processing's throughput-oriented nature. Realization of efficient stream processing requires monitoring and optimization of multiple communications links. Most techniques to optimize these links use queueing network models or network flow models, which require some idea of the actual execution rate of each independent compute kernel within the system. What we want to know is how fast can each kernel process data independent of other communicating kernels. This is known as the "service rate" of the kernel within the queueing literature. Current approaches to divining service rates are static. Modern workloads, however, are often dynamic. Shared cloud systems also present applications with highly dynamic execution environments (multiple users, hardware migration, etc.). It is therefore desirable to continuously re-tune an application during run time (online) in response to changing conditions. Our approach enables online service rate monitoring under most conditions, obviating the need for reliance on steady state predictions for what are probably non-steady state phenomena. First, some of the difficulties associated with online service rate determination are examined. Second, the algorithm to approximate the online non-blocking service rate is described. Lastly, the algorithm is implemented within the open source RaftLib framework for validation using a simple microbenchmark as well as two full streaming applications.Comment: technical repor

PACMAS state of media and communication report 2013

The PACMAS State of Media and Communication Report 2013 was undertaken through a partnership between RMIT University (Australia), the University of Goroka (Papua New Guinea) and UNITEC (New Zealand). The research for this report was developed and undertaken between June 2012 and April 2013 across 14 Pacific Island nations: Cook Islands, Federated States of Micronesia, Fiji, Kiribati, Republic of the Marshall Islands, Republic of Nauru, Niue, Republic of Palau, Papua New Guinea, Samoa, Solomon Islands, Tonga, Tuvalu, and Vanuatu. The report provides a regional overview of the PACMAS key components (Media Policy, Media Systems, Media Capacity Building and Media Content) as they emerged through 212 interviews focused upon the six PACMAS strategic areas. It also provides basic background information, an overview of the media and communications landscape and discusses in detail media and communications technicians; emergency broadcast systems, Technical and Vocational Education and Training (TVETs), media associations, climate change and non-communicable diseases (NCDs). For this reason, observations on the four PACMAS components should be understood to represent changes in the media and communication environment based upon an investigation focused on the PACMAS strategic activities. Part 1 & Part II of the report make up a Regional Overview of the State of Media and Communication in the Pacific.  The report also includes 14 separate Country Reports which provide additional information on the media and communications landscape specific to each of the Pacific Island countries included in the PACMAS program.  The country reports were written with the objectives of the PACMAS program in mind, however they may have utility for media, communication and development practitioners across the region

Scientific Cum Doctriner Approach; a Collaborative Perspective in Islamic Studies

Islam is not a mono-dimensional religion, therefore studying Islam with all its aspects is not enough with the scientific method, ie philosophical, human, historical, sociological methods. Likewise, understanding Islam with all its aspects can not be-be doctrinaire. A scientific and doctrinal approach should be used together (Scientific Cum Doctrine