12,957 research outputs found
Grammatical Evolution for the Multi-Objective Integration and Test Order Problem
Search techniques have been successfully applied for solving different software testing problems. However, choosing, implementing and configuring a search technique can be hard tasks. To reduce efforts spent in such tasks, this paper presents an offline hyper-heuristic named GEMOITO, based on Grammatical Evolution (GE). The goal is to automatically generate a Multi-Objective Evolutionary Algorithm (MOEA) to solve the Integration and Test Order (ITO) problem. The MOEAs are distinguished by components and parameters values, described by a grammar. The proposed hyper-heuristic is compared to conventional MOEAs and to a selection hyper-heuristic used in related work. Results show that GEMOITO can generate MOEAs that are statistically better or equivalent to the compared algorithms
Which Surrogate Works for Empirical Performance Modelling? A Case Study with Differential Evolution
It is not uncommon that meta-heuristic algorithms contain some intrinsic
parameters, the optimal configuration of which is crucial for achieving their
peak performance. However, evaluating the effectiveness of a configuration is
expensive, as it involves many costly runs of the target algorithm. Perhaps
surprisingly, it is possible to build a cheap-to-evaluate surrogate that models
the algorithm's empirical performance as a function of its parameters. Such
surrogates constitute an important building block for understanding algorithm
performance, algorithm portfolio/selection, and the automatic algorithm
configuration. In principle, many off-the-shelf machine learning techniques can
be used to build surrogates. In this paper, we take the differential evolution
(DE) as the baseline algorithm for proof-of-concept study. Regression models
are trained to model the DE's empirical performance given a parameter
configuration. In particular, we evaluate and compare four popular regression
algorithms both in terms of how well they predict the empirical performance
with respect to a particular parameter configuration, and also how well they
approximate the parameter versus the empirical performance landscapes
Sentinel: A Hyper-Heuristic for the Generation of Mutant Reduction Strategies
Mutation testing is an effective approach to evaluate and strengthen software
test suites, but its adoption is currently limited by the mutants' execution
computational cost. Several strategies have been proposed to reduce this cost
(a.k.a. mutation cost reduction strategies), however none of them has proven to
be effective for all scenarios since they often need an ad-hoc manual selection
and configuration depending on the software under test (SUT). In this paper, we
propose a novel multi-objective evolutionary hyper-heuristic approach, dubbed
Sentinel, to automate the generation of optimal cost reduction strategies for
every new SUT. We evaluate Sentinel by carrying out a thorough empirical study
involving 40 releases of 10 open-source real-world software systems and both
baseline and state-of-the-art strategies as a benchmark. We execute a total of
4,800 experiments, and evaluate their results with both quality indicators and
statistical significance tests, following the most recent best practice in the
literature. The results show that strategies generated by Sentinel outperform
the baseline strategies in 95% of the cases always with large effect sizes.
They also obtain statistically significantly better results than
state-of-the-art strategies in 88% of the cases, with large effect sizes for
95% of them. Also, our study reveals that the mutation strategies generated by
Sentinel for a given software version can be used without any loss in quality
for subsequently developed versions in 95% of the cases. These results show
that Sentinel is able to automatically generate mutation strategies that reduce
mutation testing cost without affecting its testing effectiveness (i.e.
mutation score), thus taking off from the tester's shoulders the burden of
manually selecting and configuring strategies for each SUT.Comment: in IEEE Transactions on Software Engineerin
Operational Research in Education
Operational Research (OR) techniques have been applied, from the early stages of the discipline, to a wide variety of issues in education. At the government level, these include questions of what resources should be allocated to education as a whole and how these should be divided amongst the individual sectors of education and the institutions within the sectors. Another pertinent issue concerns the efficient operation of institutions, how to measure it, and whether resource allocation can be used to incentivise efficiency savings. Local governments, as well as being concerned with issues of resource allocation, may also need to make decisions regarding, for example, the creation and location of new institutions or closure of existing ones, as well as the day-to-day logistics of getting pupils to schools. Issues of concern for managers within schools and colleges include allocating the budgets, scheduling lessons and the assignment of students to courses. This survey provides an overview of the diverse problems faced by government, managers and consumers of education, and the OR techniques which have typically been applied in an effort to improve operations and provide solutions
Multi-objective Optimisation of a Water Distribution Network with a Sequence-based Selection Hyper-heuristic
This is the author accepted manuscript. The final version is available from the publisher.Multi-objective hyper-heuristics are fast becoming an efficient way of optimising complex problems.
The water distribution network design problem is an example of such a problem, and this work employs a recent
hyper-heuristic that generates sequences of low-level heuristics to solve the multi-objective water distribution
design problem. The results presented are comparable to those generated by state-of-the-art metaheuristics, as
well as a single-objective version of the algorithm from the literature. The information revealed from analysing
the sequences generated to solve the problem reveal important information about the nature of the problem space
that is not available from the metaheuristics, and the entire Pareto front can be explored in a single run as opposed
to the multiple runs needed with the original single-objective algorithm
Global Trajectory Optimisation : Can We Prune the Solution Space When Considering Deep Space Manoeuvres? [Final Report]
This document contains a report on the work done under the ESA/Ariadna study 06/4101 on the global optimization of space trajectories with multiple gravity assist (GA) and deep space manoeuvres (DSM). The study was performed by a joint team of scientists from the University of Reading and the University of Glasgow
A Parallel General Purpose Multi-Objective Optimization Framework, with Application to Beam Dynamics
Particle accelerators are invaluable tools for research in the basic and
applied sciences, in fields such as materials science, chemistry, the
biosciences, particle physics, nuclear physics and medicine. The design,
commissioning, and operation of accelerator facilities is a non-trivial task,
due to the large number of control parameters and the complex interplay of
several conflicting design goals. We propose to tackle this problem by means of
multi-objective optimization algorithms which also facilitate a parallel
deployment. In order to compute solutions in a meaningful time frame a fast and
scalable software framework is required. In this paper, we present the
implementation of such a general-purpose framework for simulation-based
multi-objective optimization methods that allows the automatic investigation of
optimal sets of machine parameters. The implementation is based on a
master/slave paradigm, employing several masters that govern a set of slaves
executing simulations and performing optimization tasks. Using evolutionary
algorithms as the optimizer and OPAL as the forward solver, validation
experiments and results of multi-objective optimization problems in the domain
of beam dynamics are presented. The high charge beam line at the Argonne
Wakefield Accelerator Facility was used as the beam dynamics model. The 3D beam
size, transverse momentum, and energy spread were optimized
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