Parallelizing Deadlock Resolution in Symbolic Synthesis of Distributed Programs

Previous work has shown that there are two major complexity barriers in the synthesis of fault-tolerant distributed programs: (1) generation of fault-span, the set of states reachable in the presence of faults, and (2) resolving deadlock states, from where the program has no outgoing transitions. Of these, the former closely resembles with model checking and, hence, techniques for efficient verification are directly applicable to it. Hence, we focus on expediting the latter with the use of multi-core technology. We present two approaches for parallelization by considering different design choices. The first approach is based on the computation of equivalence classes of program transitions (called group computation) that are needed due to the issue of distribution (i.e., inability of processes to atomically read and write all program variables). We show that in most cases the speedup of this approach is close to the ideal speedup and in some cases it is superlinear. The second approach uses traditional technique of partitioning deadlock states among multiple threads. However, our experiments show that the speedup for this approach is small. Consequently, our analysis demonstrates that a simple approach of parallelizing the group computation is likely to be the effective method for using multi-core computing in the context of deadlock resolution

Synthesizing self-stabilization through superposition and backtracking

© Springer International Publishing Switzerland 2014. While the design of self-stabilization is known to be a hard problem, several sound (but incomplete) heuristics exist for algorithmic design of self-stabilization. This paper presents a sound and complete method for algorithmic design of self-stabilizing network protocols. The essence of the proposed approach is based on variable superposition and backtracking search. We have validated the proposed method by creating both a sequential and a parallel implementation in the context of a software tool, called Protocon. Moreover, we have used Protocon to automatically design self-stabilizing protocols for the problems that all existing heuristics fail to solve

Readability of foot and ankle consent forms in Queensland

BACKGROUND: The aim of this study was to conduct a readability analysis on both patient take-home information and consent forms for common foot and ankle procedures. Our hypothesis was that the objective reading skills required to read and comprehend the documentation currently in use would exceed the recommendations in place by both national and international bodies.METHODS: The current Queensland Health consent forms are divided into specific subsections. The readability of consent form subsections C and G (sections containing detailed information on risks of the procedure and pertaining to informed patient consent specifically) and patient take-home information (provided as take-home leaflet from the consent form which is procedure specific) was assessed by an online readability software program using five validated methods calculated by application of the algorithms for (i) Flesch-Kincaid grade level, (ii) the SMOG (Simple Measure of Gobbledygook), (iii) Coleman-Liau index, (iv) automated readability index and the (v) Linsear Wriste formula.RESULTS: The mean ± standard deviation reading grade level of risk (section C), grade level of patient consent (section G) and grade level for procedure-specific take-home patient information were 8.7 ± 0.9, 11.6 ± 1.2 and 7.5 ± 0.2, respectively.CONCLUSION: The readability of sections C and G of the Queensland Health consent form exceeds the recommendations by national and international bodies, but the patient take-home information appears suitable. Consideration should be given to lower the reading grade level of patient consent forms to better reflect the reading grade of the Australian population.</p

A Hybrid Method for the Verification and Synthesis of Parameterized Self-Stabilizing Protocols

© Springer International Publishing Switzerland 2015. This paper presents a hybrid method for verification and synthesis of parameterized self-stabilizing protocols where algorithmic design and mechanical verification techniques/tools are used hand-inhand. The core idea behind the proposed method includes the automated synthesis of self-stabilizing protocols in a limited scope (i.e., fixed number of processes) and the use of theorem proving methods for the generalization of the solutions produced by the synthesizer. Specifically, we use the Prototype Verification System (PVS) to mechanically verify an algorithm for the synthesis of weakly self-stabilizing protocols. Then, we reuse the proof of correctness of the synthesis algorithm to establish the correctness of the generalized versions of synthesized protocols for an arbitrary number of processes. We demonstrate the proposed approach in the context of an agreement and a coloring protocol on the ring topology