16,718 research outputs found
Compositional Algorithms for Succinct Safety Games
We study the synthesis of circuits for succinct safety specifications given
in the AIG format. We show how AIG safety specifications can be decomposed
automatically into sub specifications. Then we propose symbolic compositional
algorithms to solve the synthesis problem compositionally starting for the
sub-specifications. We have evaluated the compositional algorithms on a set of
benchmarks including those proposed for the first synthesis competition
organised in 2014 by the Synthesis Workshop affiliated to the CAV conference.
We show that a large number of benchmarks can be decomposed automatically and
solved more efficiently with the compositional algorithms that we propose in
this paper.Comment: In Proceedings SYNT 2015, arXiv:1602.0078
Effect of electropolymerisation conditions on the permeability of polyphenol films deposited on a vitreous carbon electrode
Polymeric films were prepared from alkaline (NaOH) phenol aqueous solutions on a vitreous carbon (VC) electrode by potentiostatic or galvanostatic electro-oxidation. Permeation through such films was studied by rotating-disk electrode using the ferricyanide redox couple, and by cyclic voltammetry using phenate ions. The influence of the electropolymerisation controllable parameters such as NaOH and phenol concentrations, potential or current applied, electrosynthesis time, temperature and hydrodynamic conditions (electrode rotation + solution magnetic stirring) on the permeability of these polymeric films was examined. Conditions for the removal of phenol by electropolymerisation are discussed on the basis of the permeability of polyphenol films obtained by electrosynthesis. Permeable films were formed for a concentration of free hydroxyl anion larger of 0.1 M. An increase of the temperature to 85°C favours the
formation of highly permeable films, thus avoiding electrode fouling
Coreference-Based Summarization and Question Answering: a Case for High Precision Anaphor Resolution
Approaches to Text Summarization and Question Answering are known to benefit from the availability of coreference information. Based on an analysis of its contributions, a more detailed look at coreference processing for these applications will be proposed: it should be considered as a task of anaphor resolution rather than coreference resolution. It will be further argued that high precision approaches to anaphor resolution optimally match the specific requirements. Three such approaches will be described and empirically evaluated, and the implications for Text Summarization and Question Answering will be discussed
Error Control of Iterative Linear Solvers for Integrated Groundwater Models
An open problem that arises when using modern iterative linear solvers, such
as the preconditioned conjugate gradient (PCG) method or Generalized Minimum
RESidual method (GMRES) is how to choose the residual tolerance in the linear
solver to be consistent with the tolerance on the solution error. This problem
is especially acute for integrated groundwater models which are implicitly
coupled to another model, such as surface water models, and resolve both
multiple scales of flow and temporal interaction terms, giving rise to linear
systems with variable scaling.
This article uses the theory of 'forward error bound estimation' to show how
rescaling the linear system affects the correspondence between the residual
error in the preconditioned linear system and the solution error. Using
examples of linear systems from models developed using the USGS GSFLOW package
and the California State Department of Water Resources' Integrated Water Flow
Model (IWFM), we observe that this error bound guides the choice of a practical
measure for controlling the error in rescaled linear systems. It is found that
forward error can be controlled in preconditioned GMRES by rescaling the linear
system and normalizing the stopping tolerance. We implemented a preconditioned
GMRES algorithm and benchmarked it against the Successive-Over-Relaxation (SOR)
method. Improved error control reduces redundant iterations in the GMRES
algorithm and results in overall simulation speedups as large as 7.7x. This
research is expected to broadly impact groundwater modelers through the
demonstration of a practical approach for setting the residual tolerance in
line with the solution error tolerance.Comment: 13 pages and 1 figur
- âŠ