added evo-section

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@ -115,3 +115,14 @@ eprint = {https://doi.org/10.1137/0111030}
organization={IEEE}, organization={IEEE},
url={http://www.graphics.uni-bielefeld.de/publications/cec15.pdf} url={http://www.graphics.uni-bielefeld.de/publications/cec15.pdf}
} }
@article{back1993overview,
title={An overview of evolutionary algorithms for parameter optimization},
author={B{\"a}ck, Thomas and Schwefel, Hans-Paul},
journal={Evolutionary computation},
volume={1},
number={1},
pages={1--23},
year={1993},
publisher={MIT Press},
url={https://www.researchgate.net/profile/Hans-Paul_Schwefel/publication/220375001_An_Overview_of_Evolutionary_Algorithms_for_Parameter_Optimization/links/543663d00cf2dc341db30452.pdf}
}

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@ -174,7 +174,56 @@ mesh albeit the downsides.
## What is evolutional optimization? ## What is evolutional optimization?
\label{sec:back:evo} \label{sec:back:evo}
\change[inline]{Write this section} In this thesis we are using an evolutional optimization strategy to solve the
problem of finding the best parameters for our deformation. This approach,
however, is very generic and we introduce it here in a broader sense.
\begin{algorithm}
\caption{An outline of evolutional algorithms}
\label{alg:evo}
\begin{algorithmic}
\STATE t := 0;
\STATE initialize $P(0) := \{\vec{a}_1(0),\dots,\vec{a}_\mu(0)\} \in I^\mu$;
\STATE evaluate $F(0) : \{\Phi(x) | x \in P(0)\}$;
\WHILE{$c(F(t)) \neq$ \TRUE}
\STATE recombine: $P(t) := r(P(t))$;
\STATE mutate: $P''(t) := m(P(t))$;
\STATE evaluate $F''(t) : \{\Phi(x) | x \in P''(t)\}$
\STATE select: $P(t + 1) := s(P''(t) \cup Q,\Phi)$;
\STATE t := t + 1;
\ENDWHILE
\end{algorithmic}
\end{algorithm}
The general shape of an evolutional algorithm (adapted from
\cite{back1993overview}} is outlined in Algorithm \ref{alg:evo}. Here, $P(t)$
denotes the population of parameters in step $t$ of the algorithm. The
population contains $\mu$ individuals $a_i$ that fit the shape of the parameters
we are looking for. Typically these are initialized by a random guess or just
zero. Further on we need a so-called *fitness-function* $\Phi : I \mapsto M$ that can take
each parameter to a measurable space along a convergence-function $c : I \mapsto
\mathbb{B}$ that terminates the optimization.
The main algorithm just repeats the following steps:
- **Recombine** with a recombination-function $r : I^{\mu} \mapsto I^{\lambda}$ to
generate new individuals based on the parents characteristics.
This makes sure that the next guess is close to the old guess.
- **Mutate** with a mutation-function $m : I^{\lambda} \mapsto I^{\lambda}$ to
introduce new effects that cannot be produced by mere recombination of the
parents.
Typically this just adds minor defects to individual members of the population
like adding a random gaussian noise or amplifying/dampening random parts.
- **Selection** takes a selection-function $s : (I^\lambda \cup I^{\mu + \lambda},\Phi) \mapsto I^\mu$ that
selects from the previously generated $I^\lambda$ children and optionally also
the parents (denoted by the set $Q$ in the algorithm) using the
fitness-function $\Phi$. The result of this operation is the next Population
of $\mu$ individuals.
All these functions can (and mostly do) have a lot of hidden parameters that
can be changed over time. One can for example start off with a high
mutation--rate that cools off over time (i.e. by lowering the variance of a
gaussian noise). As the recombination and selection-steps are usually pure
## Advantages of evolutional algorithms ## Advantages of evolutional algorithms
\label{sec:back:evogood} \label{sec:back:evogood}

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@ -331,7 +331,68 @@ optimization?}\label{what-is-evolutional-optimization}
\label{sec:back:evo} \label{sec:back:evo}
\change[inline]{Write this section} \change[inline]{Write this section} In this thesis we are using an
evolutional optimization strategy to solve the problem of finding the
best parameters for our deformation. This approach, however, is very
generic and we introduce it here in a broader sense.
\begin{algorithm}
\caption{An outline of evolutional algorithms}
\label{alg:evo}
\begin{algorithmic}
\STATE t := 0;
\STATE initialize $P(0) := \{\vec{a}_1(0),\dots,\vec{a}_\mu(0)\} \in I^\mu$;
\STATE evaluate $F(0) : \{\Phi(x) | x \in P(0)\}$;
\WHILE{$c(F(t)) \neq$ \TRUE}
\STATE recombine: $P(t) := r(P(t))$;
\STATE mutate: $P''(t) := m(P(t))$;
\STATE evaluate $F''(t) : \{\Phi(x) | x \in P''(t)\}$
\STATE select: $P(t + 1) := s(P''(t) \cup Q,\Phi)$;
\STATE t := t + 1;
\ENDWHILE
\end{algorithmic}
\end{algorithm}
The general shape of an evolutional algorithm (adapted from
\cite{back1993overview}\} is outlined in Algorithm \ref{alg:evo}. Here,
\(P(t)\) denotes the population of parameters in step \(t\) of the
algorithm. The population contains \(\mu\) individuals \(a_i\) that fit
the shape of the parameters we are looking for. Typically these are
initialized by a random guess or just zero. Further on we need a
so-called \emph{fitness-function} \(\Phi : I \mapsto M\) that can take
each parameter to a measurable space along a convergence-function
\(c : I \mapsto \mathbb{B}\) that terminates the optimization.
The main algorithm just repeats the following steps:
\begin{itemize}
\tightlist
\item
\textbf{Recombine} with a recombination-function
\(r : I^{\mu} \mapsto I^{\lambda}\) to generate new individuals based
on the parents characteristics.\\
This makes sure that the next guess is close to the old guess.
\item
\textbf{Mutate} with a mutation-function
\(m : I^{\lambda} \mapsto I^{\lambda}\) to introduce new effects that
cannot be produced by mere recombination of the parents.\\
Typically this just adds minor defects to individual members of the
population like adding a random gaussian noise or amplifying/dampening
random parts.
\item
\textbf{Selection} takes a selection-function
\(s : (I^\lambda \cup I^{\mu + \lambda},\Phi) \mapsto I^\mu\) that
selects from the previously generated \(I^\lambda\) children and
optionally also the parents (denoted by the set \(Q\) in the
algorithm) using the fitness-function \(\Phi\). The result of this
operation is the next Population of \(\mu\) individuals.
\end{itemize}
All these functions can (and mostly do) have a lot of hidden parameters
that can be changed over time. One can for example start off with a high
mutation--rate that cools off over time (i.e.~by lowering the variance
of a gaussian noise). As the recombination and selection-steps are
usually pure
\section{Advantages of evolutional \section{Advantages of evolutional
algorithms}\label{advantages-of-evolutional-algorithms} algorithms}\label{advantages-of-evolutional-algorithms}