scholarly journals From Parallel SAT to Distributed SAT

10.29007/44vf ◽  
2018 ◽  
Author(s):  
Youssef Hamadi
Keyword(s):  
Divide And Conquer ◽  
Communication Overhead ◽  
Sat Solving ◽  
The Impact

This tutorial will present an overview of parallelism in SAT. It will start with a presentation of classical divide and conquer techniques, discuss their ancient origin and compare them to more recent portfolio- based algorithms. It will then present the impact of clause-sharing on their performances and discuss various strategies used to control the communication overhead. A particular technique used to control the classical diversification/intensification tradeoff will also be presented. Finally, perspectives will be given which will relate the current parallel SAT technologies to the expected evolution of computational platforms, leading to distributed SAT solving scenarios.

scholarly journals Dolius: A Distributed Parallel SAT Solving Framework

10.29007/hvqt ◽  
2018 ◽  
Author(s):  
Gilles Audemard ◽  
Benoît Hoessen ◽  
Saïd Jabbour ◽  
Cédric Piette
Keyword(s):  
Shared Memory ◽  
State Of The Art ◽  
Divide And Conquer ◽  
Sat Solving ◽  
Sat Solvers ◽  
Sat Solver

Over the years, parallel SAT solving becomes more and more important. However, most of state-of-the-art parallel SAT solvers are portfolio-based ones. They aim at running several times the same solver with different parameters. In this paper, we propose a tool called Dolius, mainly based on the divide and conquer paradigm. In contrast to most current parallel efficient engines, Dolius does not need shared memory, can be distributed, and scales well when a large number of computing units is available. Furthermore, our tool contains an API allowing to plug any SAT solver in a simple way.

scholarly journals Proline-rich domain of human ALIX contains multiple TSG101-UEV interaction sites and forms phosphorylation-mediated reversible amyloids

2020 ◽  
Vol 117 (39) ◽  
pp. 24274-24284
Author(s):  
Ruben D. Elias ◽  
Wen Ma ◽  
Rodolfo Ghirlando ◽  
Charles D. Schwieters ◽  
Vijay S. Reddy ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Amyloid Fibrils ◽  
Recombinant Expression ◽  
Hydrophobic Effect ◽  
Adaptor Protein ◽  
Relaxation Dispersion ◽  
Divide And Conquer ◽  
Interaction Sites ◽  
Rich Domain ◽  
The Impact

Proline-rich domains (PRDs) are among the most prevalent signaling modules of eukaryotes but often unexplored by biophysical techniques as their heterologous recombinant expression poses significant difficulties. Using a “divide-and-conquer” approach, we present a detailed investigation of a PRD (166 residues; ∼30% prolines) belonging to a human protein ALIX, a versatile adaptor protein involved in essential cellular processes including ESCRT-mediated membrane remodeling, cell adhesion, and apoptosis. In solution, the N-terminal fragment of ALIX-PRD is dynamically disordered. It contains three tandem sequentially similar proline-rich motifs that compete for a single binding site on its signaling partner, TSG101-UEV, as evidenced by heteronuclear NMR spectroscopy. Global fitting of relaxation dispersion data, measured as a function of TSG101-UEV concentration, allowed precise quantitation of these interactions. In contrast to the soluble N-terminal portion, the C-terminal tyrosine-rich fragment of ALIX-PRD forms amyloid fibrils and viscous gels validated using dye-binding assays with amyloid-specific probes, congo red and thioflavin T (ThT), and visualized by transmission electron microscopy. Remarkably, fibrils dissolve at low temperatures (2 to 6 °C) or upon hyperphosphorylation with Src kinase. Aggregation kinetics monitored by ThT fluorescence shows that charge repulsion dictates phosphorylation-mediated fibril dissolution and that the hydrophobic effect drives fibril formation. These data illuminate the mechanistic interplay between interactions of ALIX-PRD with TSG101-UEV and polymerization of ALIX-PRD and its central role in regulating ALIX function. This study also demonstrates the broad functional repertoires of PRDs and uncovers the impact of posttranslational modifications in the modulation of reversible amyloids.

scholarly journals Investigating Parallel Programming Paradigms in HeMPS MPSoC Platform

2019 ◽  
Author(s):  
Geaninne Lopes ◽  
Aline Mello ◽  
Ewerson Carvalho ◽  
César Marcon
Keyword(s):  
Parallel Programming ◽  
Power Dissipation ◽  
Execution Time ◽  
Matrix Multiplication ◽  
Divide And Conquer ◽  
Image Manipulation ◽  
Multiprocessor System ◽  
Input Size ◽  
Programming Paradigms ◽  
The Impact

This work investigates the use of parallel programming paradigms in the development of applications targeting a Multiprocessor System-on-Chip (MPSoC). We implemented Matrix Multiplication, Image Manipulation and Advanced Encryption Standard (AES) applications in the Master-Slave, Pipeline and Divide-and-Conquer paradigms, and applied execution time and power dissipation as criteria for evaluating the performance of the applications executing according to the paradigms on an MPSoC architecture. The obtained results allowed ​us to conclude that there are optimal application-paradigm relations. Pipeline presents lower execution time and lower power dissipation for the Image Manipulation application; whereas, Master-Slave performs better for the Matrix Multiplication and AES applications. However, when the input size of the applications increases, the Divide-and-Conquer paradigm tends to minimize the execution time for Matrix Multiplication application. ​The main contributions of this work are the development of applications, considering different paradigms, and the impact evaluation of these paradigms on MPSoC architecture.

scholarly journals Tuning Parallel SAT Solvers

10.29007/z3g2 ◽  
2019 ◽  
Author(s):  
Thorsten Ehlers ◽  
Dirk Nowotka
Keyword(s):  
Model Checking ◽  
Database Management ◽  
Bounded Model Checking ◽  
Experimental Results ◽  
Massively Parallel ◽  
Sat Solving ◽  
Sat Solvers ◽  
Sat Solver ◽  
The Impact

In this paper we present new implementation details and benchmarking results for our parallel portfolio solver TopoSAT2. In particular, we discuss ideas and implementation details for the exchange of learned clauses in a massively-parallel SAT solver which is designed to run more that 1, 000 solver threads in parallel. Furthermore, we go back to the roots of portfolio SAT solving, and discuss the impact of diversifying the solver by using different restart- , branching- and clause database management heuristics. We show that these techniques can be used to tune the solver towards different problems. However, in a case study on formulas derived from Bounded Model Checking problems we see the best performance when using a rather simple clause exchange strategy. We show details of these tests and discuss possible explanations for this phenomenon.As computing times on massively-parallel clusters are expensive, we consider it especially interesting to share these kind of experimental results.

scholarly journals Adaptive Multi-Channel Clustering in IEEE 802.11s Wireless Mesh Networks

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7215
Author(s):  
Michael Rethfeldt ◽  
Tim Brockmann ◽  
Benjamin Beichler ◽  
Christian Haubelt ◽  
Dirk Timmermann
Keyword(s):  
Wireless Mesh Networks ◽  
Channel Assignment ◽  
Mesh Networks ◽  
Low Cost ◽  
Cluster Formation ◽  
Divide And Conquer ◽  
Communication Overhead ◽  
Ieee 802.11S ◽  
Dynamic Cluster ◽  
Wireless Mesh

WLAN mesh networks are one of the key technologies for upcoming smart city applications and are characterized by a flexible and low-cost deployment. The standard amendment IEEE 802.11s introduces low-level mesh interoperability at the WLAN MAC layer. However, scalability limitations imposed by management traffic overhead, routing delays, medium contention, and interference are common issues in wireless mesh networks and also apply to IEEE 802.11s networks. Possible solutions proposed in the literature recommend a divide-and-conquer scheme that partitions the network into clusters and forms smaller collision and broadcast domains by assigning orthogonal channels. We present CHaChA (Clustering Heuristic and Channel Assignment), a distributed cross-layer approach for cluster formation and channel assignment that directly integrates the default IEEE 802.11s mesh protocol information and operating modes, retaining unrestricted compliance to the WLAN standard. Our concept proposes further mechanisms for dynamic cluster adaptation, including subsequent cluster joining, isolation and fault detection, and node roaming for cluster balancing. The practical performance of CHaChA is demonstrated in a real-world 802.11s testbed. We first investigate clustering reproducibility, duration, and communication overhead in static network scenarios of different sizes. We then validate our concepts for dynamic cluster adaptation, considering topology changes that are likely to occur during long-term network operation and maintenance.

Solidarity or Distancing? How Official Status Influences Chinese Protestant Reactions to Repression

2020 ◽  
Author(s):  
Harris Doshay
Keyword(s):  
Civil Society ◽  
Divide And Conquer ◽  
Victim Blaming ◽  
Christian Churches ◽  
Group Members ◽  
The Impact ◽  
Official Status ◽  
Do So

When facing state-backed repression, why do groups sometimes band together in solidarity and sometimes fail to do so? This study contributes to the literature on repression by studying how and why repressed groups react to repression, focusing on how registered civil society groups affect solidarity. Specifically, I trace the impact of the Chinese Communist Party’s Cross Demolition Campaign on patterns of solidarity and victim blaming among Christian Churches. I further demonstrate conditions under which repressed group members become more fragmented and scattered rather than more unified. Based on evidence from sixty-four elite and mass interviews, I find that registered groups’ legibility constrains their members, thus enabling dynamics of victim-blaming that hinder solidarity and further empowering the autocrat to divide and conquer potential opposition.

scholarly journals Decomposition of 2D polygons and its effect in hydrological models

2018 ◽  
Vol 21 (1) ◽  
pp. 104-122 ◽  
Author(s):  
P. Sanzana ◽  
J. Gironás ◽  
I. Braud ◽  
N. Hitschfeld ◽  
F. Branger ◽  
...  
Keyword(s):  
Urban Areas ◽  
Geographical Information Systems ◽  
Divide And Conquer ◽  
Geographical Information ◽  
Hydrologic Connectivity ◽  
Distributed Modeling ◽  
Distributed Processes ◽  
Spatially Distributed ◽  
Convexity Index ◽  
The Impact

Abstract 2D non-uniform polygonal meshes allow representation of the impact of landscape elements and small infrastructures on water flows. The initial vectorial mesh, derived from the intersection of several geographical information systems' layers, can have highly non-convex or sliver polygons. These bad-shaped elements compromise accurate numerical flow computation. We propose a flexible divide-and-conquer strategy to decompose polygons into physiographical meaningful parts using shape descriptors to better represent the surface terrain and hydrologic connectivity. We use the convexity index (CI) and the form factor (FF) to consider convex and square like optimum shapes. The strategy was applied to two peri-urban areas whose hydrologic response was simulated using distributed modeling. Good-quality meshes were generated with threshold values of CI≈0.8 and FF≈0.2, and CI≈0.95 and FF≈0.4 for undeveloped and highly urbanized zones, respectively. We concluded that the mesh segmentation facilitates the representation of the spatially distributed processes controlling not only the lumped response of the catchment, but also the spatial variability of water quantity and fluxes within it at medium and small scales.

An Efficient Trust-Based Routing Model for Clustered-Based Hetrogeneous Wireless Sensor Network

2020 ◽  
Vol 16 (2) ◽  
pp. 84-101
Author(s):  
Gousia Thaniyath
Keyword(s):  
Energy Efficiency ◽  
Data Access ◽  
Packet Transmission ◽  
Wireless Sensor ◽  
Misclassification Rate ◽  
Communication Overhead ◽  
Time Data ◽  
Sensor Device ◽  
Sensor Devices ◽  
The Impact

Wireless sensor networks (WSN) play a very important role in providing real-time data access for big data and IoT application. The open deployment, energy constraint, and lack of centralized administration makes WSN very vulnerable to various kinds of malicious attacks. In WSN, identifying malicious sensor device and eliminating their sensed information play very important roles for mission critical applications. Standard cryptography and authentication schemes cannot be directly used in WSN because of the resource constraint nature of sensor devices. Thus, energy efficient and low latency methodology is required for minimizing the impact of malicious sensor devices. This paper presents a secure and load balanced routing (SLBR) scheme for heterogeneous clustered-based WSN. SLBR present better trust-based security metric that overcomes the problem when sensor keep oscillating for good to bad state and vice versa, and also balance load among CH. Thus, they aid in achieving better security, packet transmission, and energy efficiency performance. Experiments are conducted to evaluate the performance of proposed SLBR model over existing trust-based routing model, namely exponential cat swarm optimization (ECSO). The result attained shows SLBR models attain better performance than ECSO in terms of energy efficiency (i.e., network lifetime considering first sensor device death and total sensor device death), communication overhead, throughput, packet processing latency, malicious sensor device misclassification rate, and identification.

Sign in / Sign up

Export Citation Format

Share Document