4,509 research outputs found
Improved Runtime Bounds for the Univariate Marginal Distribution Algorithm via Anti-Concentration
Unlike traditional evolutionary algorithms which produce offspring via
genetic operators, Estimation of Distribution Algorithms (EDAs) sample
solutions from probabilistic models which are learned from selected
individuals. It is hoped that EDAs may improve optimisation performance on
epistatic fitness landscapes by learning variable interactions. However, hardly
any rigorous results are available to support claims about the performance of
EDAs, even for fitness functions without epistasis. The expected runtime of the
Univariate Marginal Distribution Algorithm (UMDA) on OneMax was recently shown
to be in by Dang and Lehre
(GECCO 2015). Later, Krejca and Witt (FOGA 2017) proved the lower bound
via an involved drift analysis.
We prove a bound, given some restrictions
on the population size. This implies the tight bound when , matching the runtime
of classical EAs. Our analysis uses the level-based theorem and
anti-concentration properties of the Poisson-Binomial distribution. We expect
that these generic methods will facilitate further analysis of EDAs.Comment: 19 pages, 1 figur
Towards a Theory-Guided Benchmarking Suite for Discrete Black-Box Optimization Heuristics: Profiling EA Variants on OneMax and LeadingOnes
Theoretical and empirical research on evolutionary computation methods
complement each other by providing two fundamentally different approaches
towards a better understanding of black-box optimization heuristics. In
discrete optimization, both streams developed rather independently of each
other, but we observe today an increasing interest in reconciling these two
sub-branches. In continuous optimization, the COCO (COmparing Continuous
Optimisers) benchmarking suite has established itself as an important platform
that theoreticians and practitioners use to exchange research ideas and
questions. No widely accepted equivalent exists in the research domain of
discrete black-box optimization.
Marking an important step towards filling this gap, we adjust the COCO
software to pseudo-Boolean optimization problems, and obtain from this a
benchmarking environment that allows a fine-grained empirical analysis of
discrete black-box heuristics. In this documentation we demonstrate how this
test bed can be used to profile the performance of evolutionary algorithms.
More concretely, we study the optimization behavior of several EA
variants on the two benchmark problems OneMax and LeadingOnes. This comparison
motivates a refined analysis for the optimization time of the EA
on LeadingOnes
Optimal Parameter Choices Through Self-Adjustment: Applying the 1/5-th Rule in Discrete Settings
While evolutionary algorithms are known to be very successful for a broad
range of applications, the algorithm designer is often left with many
algorithmic choices, for example, the size of the population, the mutation
rates, and the crossover rates of the algorithm. These parameters are known to
have a crucial influence on the optimization time, and thus need to be chosen
carefully, a task that often requires substantial efforts. Moreover, the
optimal parameters can change during the optimization process. It is therefore
of great interest to design mechanisms that dynamically choose best-possible
parameters. An example for such an update mechanism is the one-fifth success
rule for step-size adaption in evolutionary strategies. While in continuous
domains this principle is well understood also from a mathematical point of
view, no comparable theory is available for problems in discrete domains.
In this work we show that the one-fifth success rule can be effective also in
discrete settings. We regard the ~GA proposed in
[Doerr/Doerr/Ebel: From black-box complexity to designing new genetic
algorithms, TCS 2015]. We prove that if its population size is chosen according
to the one-fifth success rule then the expected optimization time on
\textsc{OneMax} is linear. This is better than what \emph{any} static
population size can achieve and is asymptotically optimal also among
all adaptive parameter choices.Comment: This is the full version of a paper that is to appear at GECCO 201
Analyses of evolutionary algorithms
Evolutionary algorithms (EAs) are a highly successful tool commonly used in practice to solve algorithmic problems. This remarkable practical value, however, is not backed up by a deep theoretical understanding. Such an understanding would facilitate the application of EAs to further problems. Runtime analyses of EAs are one way to expand the theoretical knowledge in this field.
This thesis presents runtime analyses for three prominent problems in combinatorial optimization. Additionally, it provides probability theoretical tools that will simplify future runtime analyses of EAs.
The first problem considered is the Single Source Shortest Path problem. The task is to find in a weighted graph for a given source vertex shortest paths to all other vertices. Developing a new analysis method we can give tight bounds on the runtime of a previously designed and analyzed EA for this problem.
The second problem is the All-Pairs Shortest Path problem. Given a weighted graph, one has to find a shortest path for every pair of vertices in the graph. For this problem we show that adding a crossover operator to a natural EA using only mutation provably decreases the runtime. This is the first time that the usefulness of a crossover operator was shown for a combinatorial problem.
The third problem considered is the Sorting problem. For this problem, we design a new representation based on trees. We show that the EA nat- urally arising from this representation has a better runtime than previously analyzed EAs.Evolutionäre Algorithmen (EAs) werden in der Praxis sehr erfolgreich eingesetzt. Bisher werden die theoretischen Grundlagen von EAs jedoch nicht zufriedenstellend verstanden. Laufzeitanalysen für einfache EAs sollen dieses Verständnis erweitern.
Diese Dissertation enthält Laufzeitanalysen für EAs für drei wohlbekannte kombinatorische Probleme. Zusätzlich werden wahrscheinlichkeitstheoretische Hilfsmittel zur Analyse von EAs eingeführt.
Zuerst behandeln wir das Single Source Shortest Path Problem. Die Aufgabe besteht darin, in einem gewichteten Graphen einen kürzesten Weg von einem Startknoten zu jedem anderen Knoten zu finden. Durch die Entwick- lung einer neuen Analysemethode konnten wir scharfe Schranken für die Laufzeit eines bereits zuvor präsentierten und analysierten EAs angeben.
Als nächstes betrachten wir das All-Pairs Shortest Path Problem. Hierbei will man für jedes Paar von Knoten in einem gewichteten Graphen einen kürzesten Weg berechnen. Für dieses Problem zeigen wir, dass das Hinzufügen eines Crossover Operators die Laufzeit gegenüber einem natürlichen EA, der nur Mutationen nutzt, verbessert. Dies ist das erste Mal, dass für ein kombinatorisches Problem bewiesen wurde, dass ein Crossover Operator die Laufzeit reduziert.
Für das Sortierproblem entwickeln wir eine neue, auf Bäumen beruhende Repräsentation und zeigen, dass der natürlich daraus entstehende EA eine bessere Laufzeit hat als vorherige EAs
Runtime Analysis of the Genetic Algorithm on Random Satisfiable 3-CNF Formulas
The genetic algorithm, first proposed at GECCO 2013,
showed a surprisingly good performance on so me optimization problems. The
theoretical analysis so far was restricted to the OneMax test function, where
this GA profited from the perfect fitness-distance correlation. In this work,
we conduct a rigorous runtime analysis of this GA on random 3-SAT instances in
the planted solution model having at least logarithmic average degree, which
are known to have a weaker fitness distance correlation.
We prove that this GA with fixed not too large population size again obtains
runtimes better than , which is a lower bound for most
evolutionary algorithms on pseudo-Boolean problems with unique optimum.
However, the self-adjusting version of the GA risks reaching population sizes
at which the intermediate selection of the GA, due to the weaker
fitness-distance correlation, is not able to distinguish a profitable offspring
from others. We show that this problem can be overcome by equipping the
self-adjusting GA with an upper limit for the population size. Apart from
sparse instances, this limit can be chosen in a way that the asymptotic
performance does not worsen compared to the idealistic OneMax case. Overall,
this work shows that the GA can provably have a good
performance on combinatorial search and optimization problems also in the
presence of a weaker fitness-distance correlation.Comment: An extended abstract of this report will appear in the proceedings of
the 2017 Genetic and Evolutionary Computation Conference (GECCO 2017
An Exponential Lower Bound for the Runtime of the cGA on Jump Functions
In the first runtime analysis of an estimation-of-distribution algorithm
(EDA) on the multi-modal jump function class, Hasen\"ohrl and Sutton (GECCO
2018) proved that the runtime of the compact genetic algorithm with suitable
parameter choice on jump functions with high probability is at most polynomial
(in the dimension) if the jump size is at most logarithmic (in the dimension),
and is at most exponential in the jump size if the jump size is
super-logarithmic. The exponential runtime guarantee was achieved with a
hypothetical population size that is also exponential in the jump size.
Consequently, this setting cannot lead to a better runtime.
In this work, we show that any choice of the hypothetical population size
leads to a runtime that, with high probability, is at least exponential in the
jump size. This result might be the first non-trivial exponential lower bound
for EDAs that holds for arbitrary parameter settings.Comment: To appear in the Proceedings of FOGA 2019. arXiv admin note: text
overlap with arXiv:1903.1098
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