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that are used in selection and in replacement procedures, and a global
tournament-based selection of a whole bunch of individuals, the <b><tt><font color="#009900">EP
Tournament</font></tt></b>. Though the single-selection tournaments can
be repeated to select more than one individual, and the batch tournament
selection can be used to select a single individual, both uses are probably
a waste of CPU time.
<ul>
<li>
<a NAME="detTournament"></a><b><tt><font color="#009900">Deterministic
Tournament</font></tt></b> of size T returns the best of T uniformly chosen
individuals in the population. Its size T should be an integer >= 2. It
is implemented in the <b><tt><font color="#009900">eoDetTournamentSelect</font></tt></b>
class, a sub-class of eoSelectOne, as well as in the <b><tt><font color="#009900">eoDetTournamentTruncate</font></tt></b>
class that repeatidly removes from the population the "winner" of the inverse
tournament.&nbsp; These objects use the C++ function determinitic_tournament
in&nbsp; <a href="../../doc/html/selectors_h-source.html">selectors.h</a>.</li>

<li>
<a NAME="stochTournament"></a><b><tt><font color="#009900">Stochastic Tournament</font></tt></b>
of rate R first choses two individuals from the population, and selects
the best one with probability R (the worse one with probability 1-R). Real
parameter R should be in [0.5,1]. It is implemented in the <b><tt><font color="#009900">eoStochTournamentSelect</font></tt></b>
class, a sub-class of eoSelectOne, as well as in the <b><tt><font color="#009900">eoStochTournamentTruncate</font></tt></b>
class that repeatidly removes from the population the "winner" of the inverse
tournament.&nbsp; These objects use the C++ function determinitic_tournament
in&nbsp; <a href="../../doc/html/selectors_h-source.html">selectors.h</a>.</li>

<br><b><font color="#FF0000">Note</font></b>: A stochastic tournament with
rate 1.0 is strictly identical to a deterministic tournament of size 2.
<li>
<a NAME="EPTournament"></a><b><tt><font color="#009900">EP Tournament</font></tt></b>
of size T is a global tournament: it works by assigning a score to all
individuals in the population the following way: starting with a score
of 0, each individual I is "opposed" T times to a uniformly chosen individual.
Everytime I wins, its score in incremented by 1 (and by 0.5 for every draw).
The individuals are then selected deterministically based on their scores
from that procedure. The <b><tt><font color="#009900">EP Tournament</font></tt></b>
is implemented in the&nbsp; <b><tt><font color="#009900">eoEPReduce</font></tt></b>
truncation method used in the <b><tt><font color="#009900">eoEPReplacement</font></tt></b>
procedure.</li>

<br><b><font color="#FF0000">Note</font></b>: whereas both the determinitic
and the stochastic tournament select one individual, the EP tournament
is designed for batch selection. Of course it could be used to select a
single individual, but at a rather high computational cost.</ul>

<p><br>
<hr WIDTH="100%">
<br><a NAME="merge"></a><b><font color="#000099"><font size=+2>Merging
populations</font></font></b>
<p>In replacement procedures, one frequently needs to merge two populations
(computed form old parents and new-born offspring). Classes derived from
the abstract class eoMerge are written for that purpose.
<br>
<hr WIDTH="50%">
<br><b><font color="#000099">eoMerge</font></b>: <b><font color="#FF0000">interface</font></b>
<br>The abstract class for merging procedures is the functor class
<font color="#009900">eoMerge</font>,
and the interface for its <tt><font color="#993300">operator()</font></tt>
is
<center>
<p><b><tt><font color="#993300">void operator()(const eoPop&lt;EOT>&amp;
_parents, eoPop&lt;EOT>&amp; _offspring)</font></tt></b></center>

<p>which you could have guessed from the inheritance tree for class <b><font face="Arial,Helvetica"><font size=+1><a href="../../doc/html/classeo_merge.html">eoMerge</a></font></font></b>,
as you see there that <font color="#009900">eoMerge</font> derives from
<br><tt><font color="#993300">class eoBF&lt;const eoPop&lt;EOT>&amp;, eoPop&lt;EOT>&amp;,
void></font></tt>.
<br>This means that it takes <font color="#FF6600">2 populations</font>
and modifies the seond one by adding some individuals from the first one
(which is supposed to remain <b><tt><font color="#993300">const</font></tt></b>ant).
<br>
<hr WIDTH="50%">
<br><b><font color="#000099">eoMerge</font></b>: <b><font color="#FF0000">instances</font></b>
<br>Available <font color="#FF6600">instances of eoMerge</font> objects
are <b><tt><font color="#009900">eoPlus</font></tt></b>, that simply adds
the parents to the offspring, or <b><tt><font color="#009900">eoElitism</font></tt></b>,
that adds only some of the (best) parents to the offspring. A special case
of eoElistism is <b><tt><font color="#009900">eoNoElitism</font></tt></b>,
an eoMerge that does nothing.
<p>
<hr WIDTH="100%">
<br><a NAME="reduce"></a><b><font color="#000099"><font size=+2>Reducing
populations</font></font></b>
<p>The other useful component of replacement procedures, <font color="#009900">eoReduce</font>,
<font color="#FF6600">kills
some individuals</font> from a given population.
<br>
<hr WIDTH="50%">
<br><b><font color="#000099">eoReduce</font></b>: <b><font color="#FF0000">interface</font></b>
<br>The abstract class for reducing procedures is the functor class
<font color="#009900">eoReduce</font>,
and the interface for its <tt><font color="#993300">operator()</font></tt>
is
<center>
<p><b><tt><font color="#993300">void operator()(eoPop&lt;EOT>&amp; _parents,
unsigned int new_size)</font></tt></b></center>

<p>which you could have guessed from the inheritance tree for class <b><font face="Arial,Helvetica"><font size=+1><a href="../../doc/html/classeo_reduce.html">eoReduce</a></font></font></b>,
as you see there that <font color="#009900">eoReduce</font> derives from
<br><tt><font color="#993300">class eoBF&lt;eoPop&lt;EOT>&amp;, unsigned
int, void></font></tt>.
<br>An <font color="#009900">eoReduce</font> shoud take a<font color="#FF6600">
population</font> and shrink it to the required size.
<br>
<hr WIDTH="50%">
<br><b><font color="#000099">eoReduce</font></b>: <b><font color="#FF0000">instances</font></b>
<br>Available <font color="#FF6600">instances of eoReduce</font> are
<ul>
<li>
<b><tt><font color="#009900">eoTruncate</font></tt></b>, deterministically
kills the worse individuals, keeping only the required number. It starts
by sorting teh populations, and hence does <font color="#FF6600">modify
its order</font>.</li>

<li>
<b><tt><font color="#009900">eoLinearTruncate</font></tt></b>, deterministically
kills the worse individuals, keeping only the required number. It does
so by repeatedly removing the worsr individual. Hence does <font color="#FF6600">not
modify its order</font>, but takes longer time than <b><tt><font color="#009900">eoTruncate</font></tt></b>
in case of many offspring.</li>

<li>
<b><tt><font color="#009900">eoEPReduce</font></tt></b>, uses the <a href="#EPtournament">EP
stochastic tournament</a> to reduce the population. It requires an additinal
argument, the tournament size.</li>

<li>
<b><tt><font color="#009900">eoDetTournamentTruncate</font></tt></b> uses
inverse deterministic tournament to repeatidly kill one individual until
the propoer size is reached. As <b><tt><font color="#009900">eoLinearTruncate</font></tt></b>,
it might take some time in the case of many offspring. It requires the
size of the tournament (<b><tt><font color="#993300">unsigned int</font></tt></b>)
as parameter in the constructor (default is 2).</li>

<li>
<b><tt><font color="#009900">eoStochTournamentruncate</font></tt></b>&nbsp;
uses inverse stochastic tournament to repeatidly kill individuals from
the population. It requires the rate of the tournament (<b><tt><font color="#993300">double</font></tt></b>)
as parameter in the constructor (default is 0.75).</li>
</ul>

<hr WIDTH="100%">
<br><a NAME="howmany"></a><b><font color="#000099"><font size=+2>eoHowMany:
Choosing a number of individuals</font></font></b>
<p>Many classes in selection/replacement procedures will handle a number
of individuals that may either be fixed or be related to some argument-population
size.
<br>Of course, it is possible to write different classes that will only
differ by the way they compute the number of individuals they have to treat,
as it is done for selectors with the two classes <font color="#009900">eoSelectPerc</font>
and <font color="#009900">eoSelectNumber</font> (it could also have been
possible to have some pure abstrat class and implement the computation
of the number of individuals to treat in some derived classes).
<br>However, the class <b><tt><font color="#993300">eoHowMany</font></tt></b>
allows one to handle in a single class three different behaviors when given
a poopulatio size as argument:
<ul>
<li>
return a given rate of the argument population size</li>

<li>
return an absolute (unsigned) integer, whatever the argument population
size</li>

<li>
return the argument population size minus a given number</li>
</ul>

<hr WIDTH="50%">
<br><b><font color="#000099">eoHowMany</font></b>: <b><font color="#FF0000">interface</font></b>
<br>The class interface for its <tt><font color="#993300">operator()</font></tt>
is
<center>
<p><b><tt><font color="#993300">unsigned int operator()(unsigned int _pop_size)</font></tt></b></center>

<p>which you could have guessed from the inheritance tree for class <b><font face="Arial,Helvetica"><font size=+1><a href="../../doc/html/classeo_how_many.html">eoHowMany</a></font></font></b>,
as you see there that <b><tt><font color="#993300">eoHowMany</font></tt></b>
derives from
<br><tt><font color="#993300">class eoUF&lt;unsigned int, unsigned int></font></tt>.
<p>It has 3 possible constructors, that determine its behavior:
<ul>
<li>
<b><tt><font color="#993300">eoHowMany(double _rate, bool _interpret_as_rate
= true)</font></tt></b> where <b><tt><font color="#993300">_rate</font></tt></b>
is by default the fixed rate of behavior 1 above. However, if the boolean
second argument is false, the rate is transformed into a positive integer,
and is used for behavior 2 above</li>

<li>
<b><tt><font color="#993300">eoHowMany(int _combien)</font></tt></b>: if
<b><tt><font color="#993300">_combien</font></tt></b>
is positive, it is the absolute number of behavior 2 above, and if <b><tt><font color="#993300">_combien</font></tt></b>
is negative, its absolute value is used to decrease the argument population
in behavior 3 above</li>

<li>
<b><tt><font color="#993300">eoHowMany(unsigned int _combien)</font></tt></b>:
<b><tt><font color="#993300">_combien</font></tt></b>
(positive!)&nbsp; is the absolute number of behavior 2 above. <b><font color="#FF6600">Note</font></b>
that this constructor is mandatory to avoid ambiguity, as an unsigned int
can be casted to either an int or a double.</li>
</ul>
It is used in <font color="#009900">eoSelectMany</font> (which supersedes
<font color="#009900">eoSelectPerc</font>
and <font color="#009900">eoSelectNumber</font>, but they are left there
for tutorial reasons!) as well as in many <a href="#reduce">truncation</a>
methods, and it is used a lot in the eoGeneralReplacement construct.
<p>
<hr WIDTH="100%">
<br><a NAME="SAD"></a><b><font color="#000099"><font size=+2>Survive and
Die</font></font></b>
<br>This class is highly politically incorrect: it implements strong elitism
and eugenism :-)
<br>It starts by killing the worse individuals from the source argument,
then appends the best ones to the destination argument and removes them
from the source argument. It is used in <b><tt><a href="#SADreplacement">eoSurviveAndDieReplacement</a></tt></b>,
where the same dest is used successively for the parents and the offspring.
<p><b><font color="#000099">eoSurviveAndDie</font></b>: <b><font color="#FF0000">interface</font></b>
<br>The class interface for its <tt><font color="#993300">operator()</font></tt>
is
<center>
<p><b><tt><font color="#993300">void operator()(eoPop&lt;EOT>&amp; _source,
eoPop&lt;EOT>&amp; _dest)</font></tt></b></center>

<p>which you could have guessed from the inheritance tree for class <b><font face="Arial,Helvetica"><font size=+1><a href="../../doc/html/classeo_survive_and_die.html">eoSurviveAndDie</a></font></font></b>,
as you see there that <b><tt><font color="#993300">eoSurviveAndDie</font></tt></b>
derives from <tt><font color="#993300">class eoBF&lt;eoPop&lt;EOT>&amp;,
eoPop&lt;EOT>&amp;, void></font></tt>.
<p>Its constructor takes 3 argumenrts:
<center>
<p><b><tt><font color="#993300">eoHowMany(double _survive, double _die,
bool _interpret_as_rate = true)</font></tt></b></center>

<p>to indicate how many (or what proportion, according to <b><tt><font color="#993300">_interpret_as_rate</font></tt></b>)
of the source should be copied to the dest population, and how many (or
what proportion, according to <b><tt><font color="#993300">_interpret_as_rate</font></tt></b>)&nbsp;
should be erased from the source.
<p>
<hr WIDTH="100%"><b><font color="#CC0000">Local: </font></b><a href="#introduction">Introduction</a>&nbsp;
- <a href="#selection">Selection</a> - <a href="#replacement">Replacement</a>
- <a href="#general">General Replacement</a> - <a href="#popular">Popular
evolution engines</a> - <a href="#tournament">Tournaments</a> - <a href="#merge">Merge</a>
- <a href="#reduce">Reduce</a> - <a href="#howmany">HowMany</a> - <a href="#SAD">SurviveAndDie</a>
<br>
<hr WIDTH="100%">
<br><b><font color="#CC0000">General: </font></b><a href="eoTopDown.html">Algorithm-Based</a>
- <a href="eoBottomUp.html">Component-Based</a> - <a href="eoProgramming.html">Programming
hints</a> - <b><font face="Arial,Helvetica"><font size=+1><a href="../../doc/html/index.html">EO
documentation</a></font></font></b>
<hr WIDTH="100%">
<address>
<a href="mailto:[e-mail]">Marc Schoenauer</a></address>

<br><!-- Created: Mon Oct 30 07:27:13 CET 2000 --><!-- hhmts start -->Last
modified: Tue. Jan. 9 2001&nbsp;<!-- hhmts end -->
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