Table Of ContentFoundations of Generic Optimization
MATHEMATICAL MODELLING:
Theory and Applications
VOLUME 20
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A. Stevens (Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany)
H.-J. Zimmerman (Aachen, Germany)
The titles published in this series are listed at the end of this volume.
Foundations of Generic
Optimization
Volume 1: A Combinatorial Approach to Epistasis
by
M. Iglesias
Universidade da Coruña,
A Co r u ñ Sap, a i n
B . N a u d t s
Un i v e r s i t e i t pAenn t, w e r
An t w e r p e ng,i uBme l
A . V e r s c h o r e n
Un i v e r s i t e i t pAenn t, w e r
An t w e r p e ng,i uBme l
and
C . V i d a l
Un i v e r s i d a d e d a, C o r u ñ a
A Co r u ñ Sap, a i n
e di t de by
R . L o w e n a n d A . V e r s c h o r e n
U n i v e r s iAtnetiwt e r p e n ,
A n t w e r p e ng,i uBme l
A C.I.P. Catalogue record for this book is available from the Library of Congress.
ISBN-10 1-4020-3666-3 (HB)
ISBN-13 978-1-4020-3666-8 (HB)
ISBN-10 1-4020-3665-5 (e-book)
ISBN-13 978-1-4020-3665-1 (e-book)
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Do or do not – there is no try
(Yoda, The Empire Strikes Back)
Preface
This book deals with combinatorial aspects of epistasis, a notion that existed for
years in genetics and appeared in the field of evolutionary algorithms in the early
1990s. Even though the first chapter puts epistasis in the perspective of evolutionary
algorithms and artificial intelligence, and applications occasionally pop up in other
chapters, this book is essentially about mathematics, about combinatorial techniques
to compute in an efficient and mathematically elegant way what will be defined as
normalized epistasis. Some of the material in this book finds its origin in the PhD
theses of Hugo Van Hove [97] and Dominique Suys [95]. The sixth chapter also
contains material that appeared in the dissertation of Luk Schoofs [84]. Together
with that of M. Teresa Iglesias [36], these dissertations form the backbone of a
decade of mathematical ventures in the world of epistasis.
The authors wish to acknowledge support from the Flemish Fund of Scientific re-
search (FWO-Vlaanderen) and of the Xunta de Galicia. They also wish to explicitly
mention the intellectual and moral support they received throughout the preparation
of this work from their family and their colleagues Emilio Villanueva, Jose Mar´a
Barja and Arnold Beckelheimer, as well as our local TEXpert Jan Adriaenssens.
Contents
O Genetic algorithms: a guide for absolute beginners 1
I Evolutionary algorithms
and their theory 21
1 Basic concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2 The GA in detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3 Describing the GA dynamics . . . . . . . . . . . . . . . . . . . . . . . 29
4 rosTfGoloAngi.sde........................... 13
5 On the role of toy problems. . . . . . . . . . . . . . . . . . . . . . . . . 33
5.1 Flat fitness . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.2 One needle, two needles . . . . . . . . . . . . . . . . . . . . . 34
5.3 Unitation functions . . . . . . . . . . . . . . . . . . . . . . . . 36
5.4 nosyinutdnelcfi.rf.C-r.evos.sor............... 83
6 . . . and more serious search problems . . . . . . . . . . . . . . . . . . 44
7 Anomeiboltpyrocrffitdiedpiu.rplrc................. 4 6
7.1 noitalenacr.trosc.d–is.snet.Fi............... 4 6
7.2 nositIcar.ent........................... 4 7
7.3 The epistasis measure ...................... 49
II Epistasis 51
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2 Vnosiuostfiidneira............................ 25
x Contents
2.1 Epistasis variance . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.2 Normalized epistasis variance . . . . . . . . . . . . . . . . . . 54
2.3 noitaElesro.cipsa.ts.i.................... 5 5
3 Matrix formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.1 The matrices Gℓ and Eℓ ..................... 5 5
3.2 The rank of the matrix Gℓ .................... 60
4 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5 Extreme values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.1 The minimal value of normalized epistasis . . . . . . . . . . . 65
5.2 The maximal value of normalized epistasis . . . . . . . . . . . 71
IIIExamples 77
1 Royal Road functions . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
1.1 Generalized Royal Road functions of type I . . . . . . . . . . . 78
1.2 Generalized Royal Road functions of type II .......... 87
1.3 sStmoumlselaei.ntrexpre................... 9 2
2 nosUnoiutnic.tfat.ni.......................... 93
2.1 seiGt.i.larne.e......................... 9 3
2.2 noixmMtaroiulfr.ta....................... 94
2.3 The epistasis of a unitation function . . . . . . . . . . . . . . 95
2.4 The matrix Bℓ .......................... 96
2.5 Experimental results . . . . . . . . . . . . . . . . . . . . . . . 100
3 Template functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
3.1 Basic properties . . . . . . . . . . . . . . . . . . . . . . . . . . 103
3.2 Epistasis of template functions . . . . . . . . . . . . . . . . . . 110
3.3 Experimental results . . . . . . . . . . . . . . . . . . . . . . . 116
IV Walsh transforms 119
1 The Walsh transform . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
1.1 Walsh functions . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Contents xi
1.2 Properties of Walsh functions . . . . . . . . . . . . . . . . . . 121
1.3 The Walsh matrix . . . . . . . . . . . . . . . . . . . . . . . . . 124
2 Link with schema averages . . . . . . . . . . . . . . . . . . . . . . . . 127
3 Link with partition coefficients . . . . . . . . . . . . . . . . . . . . . . 132
4 Link with epistasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
5 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
5.1 Some first, easy examples . . . . . . . . . . . . . . . . . . . . 141
5.2 A dmenostaecxmraoi:meoemecuetintactpflpl.......541
6 Minimal epistasis and Walsh coefficients . . . . . . . . . . . . . . . . 151
V Multary epistasis 155
1 Multary representations . . . . . . . . . . . . . . . . . . . . . . . . . 155
2 Epistasis in the multary case . . . . . . . . . . . . . . . . . . . . . . . 157
2.1 The epistasis value of a function . . . . . . . . . . . . . . . . . 158
2.2 Matrix representation . . . . . . . . . . . . . . . . . . . . . . . 158
2.3 Comparing epistasis . ...................... 166
3 Extreme values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
3.1 Minimal epistasis . . . . . . . . . . . . . . . . . . . . . . . . . 169
3.2 Msi.samts.xailapie.......................71 2
4 Example: Generalized unitation functions . . . . . . . . . . . . . . . 181
4.1 Normalized epistasis . . . . . . . . . . . . . . . . . . . . . . . 182
4.2 Extreme values of normalized epistasis . . . . . . . . . . . . . 196
VI Generalized Walsh transforms 205
1 Generalized Walsh transforms . . . . . . . . . . . . . . . . . . . . . . 205
1.1 First generalization to the multary case . . . . . . . . . . . . . 206
1.2 noioStatzhetyinoradmectesalacrunleg...........12 8
2 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
2.1 Minimal epistasis . . . . . . . . . . . . . . . . . . . . . . . . . 225
2.2 Generalized camel functions . . . . . . . . . . . . . . . . . . . 228
xii Contents
2.3 Generalized unitation functions . . . . . . . . . . . . . . . . . 229
2.4 Snosnodceirutdnecro.f.....................32 1
3 Odsnadndes ..............................2 36
3.1 Notations and terminology . . . . . . . . . . . . . . . . . . . . 237
3.2 Bdenacumlasmerohest .....................2 37
3.3 Partition coefficients revisited . . . . . . . . . . . . . . . . . . 239
3.4 Application: moments of schemata and fitness function . . . . 242
3.5 ysronracno:AbfuimCistaSPscmsiy.taraplt.s......42
A The schema theorem
(variations on a theme) 249
1 A Fuzzy Schema Theorem . . . . . . . . . . . . . . . . . . . . . . . . 250
2 The schema theorem on measure spaces . . . . . . . . . . . . . . . . . 255
B Algebraic background 261
1 Matrices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
1.1 seiGt.i.larne.e.........................62 1
1.2 secblmiIirtar.env.......................2 65
1.3 sesdGerzenvila.rne......................2 67
2 Vector spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
2.1 seiGt.i.larne.e.........................2 68
2.2 Linear independence, generators and bases . . . . . . . . . . . 269
2.3 Euclidean spaces . . . . . . . . . . . . . . . . . . . . . . . . . 273
3 Lranemipas................................572
3.1 Definition and examples . . . . . . . . . . . . . . . . . . . . . 275
3.2 Linear maps and matrices . . . . . . . . . . . . . . . . . . . . 276
3.3 Orthogonal projections . . . . . . . . . . . . . . . . . . . . . . 277
4 Diagonalization . . . ...........................2 78
4.1 Eigenvalues and eigenvectors . . . . . . . . . . . . . . . . . . . 278
4.2 Diagonalizable matrices . ....................2 80