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added algorithm of Stoer and Wagner

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Martin Thoma 2013-02-20 10:47:39 +01:00
parent 1d2bd1f9f3
commit fdc5bb932f
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SOURCE = Stoer-Wagner
DELAY = 80
DENSITY = 300
WIDTH = 500
make:
pdflatex $(SOURCE).tex -output-format=pdf
make clean
clean:
rm -rf $(TARGET) *.class *.html *.log *.aux *.data *.gnuplot
gif:
pdfcrop $(SOURCE).pdf
convert -verbose -delay $(DELAY) -loop 0 -density $(DENSITY) $(SOURCE)-crop.pdf $(SOURCE).gif
make clean
png:
make
make svg
inkscape $(SOURCE).svg -w $(WIDTH) --export-png=$(SOURCE).png
transparentGif:
convert $(SOURCE).pdf -transparent white result.gif
make clean
svg:
make
#inkscape $(SOURCE).pdf --export-plain-svg=$(SOURCE).svg
pdf2svg $(SOURCE).pdf $(SOURCE).svg
# Necessary, as pdf2svg does not always create valid svgs:
inkscape $(SOURCE).svg --export-plain-svg=$(SOURCE).svg
rsvg-convert -a -w $(WIDTH) -f svg $(SOURCE).svg -o $(SOURCE)2.svg
inkscape $(SOURCE)2.svg --export-plain-svg=$(SOURCE).svg
rm $(SOURCE)2.svg

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\documentclass{article}
\usepackage[pdftex,active,tightpage]{preview}
\setlength\PreviewBorder{2mm}
\usepackage[utf8]{inputenc} % this is needed for umlauts
\usepackage[ngerman]{babel} % this is needed for umlauts
\usepackage[T1]{fontenc} % this is needed for correct output of umlauts in pdf
\usepackage{amssymb,amsmath,amsfonts} % nice math rendering
\usepackage{braket} % needed for \Set
\usepackage{algorithm,algpseudocode}
\begin{document}
\begin{preview}
Sei $S \subseteq V$ und $c:E\rightarrow\mathbb{R}_0^+$ die
Kantengewichtsfunktion.
Für $v \in V \setminus S$ sei:
\begin{align*}
c &:\mathcal{P}(V) \times V \rightarrow \mathbb{R}_0^+\\
c(S,v) &:= \sum_{\substack{\Set{u,v} \in E\\ u \in S}} c(\Set{u,v})
\end{align*}
Sei nun $d: \mathcal{P}(V) \rightarrow V$ die Funktion, die den
Knoten liefert, der am stärksten mit $S \in \mathcal{P}(V)$
verbunden ist:
\[d(S) := v \in V \setminus S: c(S, v) = \max(\Set{c(S,v) | v \in V \setminus S})\]
\begin{algorithm}[H]
\begin{algorithmic}
\Function{StoerWagner}{Network $N(D, s, t, c)$}
\State Graph $G_0 = D$
\State Knoten $a,b,v$
\State Phasenergebnisse $P$ \Comment{Speichert Schnitt und Gewicht}
\For{($i=1$; $\;i<|V|$; $\;i$++)}
\State Knotenmenge $S_i \gets \Set{}$
\State $S_i$.add($S_i \in G_i$) \Comment{Wähle einen beliebigen Startknoten}
\While{$S_i \neq V_{i-1}$}
\State $v \gets$ \Call{d}{$S_i$}
\State $S_i$.add($v$)
\EndWhile
\State $a \gets v$
\State $b \gets$ \Call{d}{$\Set{a}$}
\State $V_i \gets$ \Call{Verschmelzen}{$V_{i-1}$, $a$, $b$}
\State $E_i \gets$ \Call{Verschmelzen}{$E_{i-1}$, $a$, $b$}
\State $G_i = (V_i, E_i)$
\State $P$.add($(a, V \setminus a)$, $c(a, V \setminus a)$)
\EndFor
\State \Return $P$.getMinimalCut()
\EndFunction
\Function{Verschmelzen}{Knotenmenge $V$, Knoten $a$, Knoten $b$}
\State $V$.remove($a$)
\State $V$.remove($b$)
\State \Comment{TODO: was, wenn a und b schon Mengen sind?}
\State $V$.add($\Set{a, b}$)
\EndFunction
\Function{Verschmelzen}{Kantenmenge $E$, Knoten $a$, Knoten $b$}
\State \Comment{TODO: Kantengewichtsfunktion muss auch angepasst werden}
\ForAll{Kante $e:=(x,y) \in E$}
\If{$x == a \lor x == b$}
\State $E$.remove($e$)
\State $E$.add($(\Set{a, b},y)$)
\ElsIf{$y == a \lor y == b$}
\State $E$.remove($e$)
\State $E$.add($(x, \Set{a, b})$)
\EndIf
\EndFor
\EndFunction
\end{algorithmic}
\caption{Algorithmus von Stoer und Wanger}
\label{alg:seq1}
\end{algorithm}
\end{preview}
\end{document}