refactor: Improve sectioning

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Samuel Ortion 2024-03-26 11:13:08 +01:00
parent e64a1d711a
commit c9b2710f98
13 changed files with 692 additions and 723 deletions

2
.gitignore vendored
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build/
.bak*
**/.bak*
.auctex-auto
## Core latex/pdflatex auxiliary files:

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\chapter{Back to basics}
\begin{algorithm}
\caption{Search an element in an array}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element}
\For {($i = 0$; $i < n$; $i++$)}
\If {$A[i] = E$}
\State \Return \True
\EndIf
\EndFor
\State \Return \False
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Search an element in an array using a while loop}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element}
\State $i \gets 0$
\While {$i < n$}
\If {$A[i] = E$}
\State \Return \True
\EndIf
\State $i \gets i + 1$
\EndWhile
\State
\Return
\False
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Search an element in an array using a while loop (bis)}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element}
% \Comment{Version ``preffered" by the professor}
\State $i \gets 0$
\While {$i < n$ and $A[i] \neq E$}
\State $i \gets i + 1$
\EndWhile
\If {$i = n$}
\State
\Return \False \Else \State \Return \True \EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Count the occurrences of an element in an array}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element} \State $c \gets 0$
\For{($i = 0$; $i < n$; $i++$)}
\If {$A[i] = E$}
\State $c \gets c + 1$
\EndIf
\EndFor
\State \Return $c$
\EndFunction
\end{algorithmic}
\end{algorithm}
\part{Motifs algorithms}

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\chapter{Motif}
\section{Searching a substring in a string}
\begin{algorithm}
\caption{Brute-force search of a motif in a sequence}
\begin{algorithmic}[1]
@ -72,3 +74,369 @@
\EndFunction
\end{algorithmic}
\end{algorithm}
\section{Using matrices to search motifs}
Let $S_{1}$ and $S_{2}$ be two sequences.
$S_{1} = $ ACGUUCC
$S_{2} = $ GUU
\begin{table}
\centering
\begin{tabular}{c|ccccccc}
& A & C & G & U & U & C & C \\
\hline
G & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\
U & 0 & 0 & 0 & 1 & 1 & 0 & 0 \\
U & 0 & 0 & 0 & 1 & 1 & 0 & 0
\end{tabular}
\caption{Comparison matrix}
\end{table}
Let $n = |S_{1}|$, $m = |S_{2}|$
The complexity of this algorithm is $\mathcal{O}(n \cdot m)$ to build the matrix, and it requires also to find the diagonals and thus it is a bit less efficient than the \autoref{alg:naive-motif-matching}.
To find repetitions, we can use a comparison matrix with a single sequence against itself. A repetition would appear as a diagonal of ones, not on the main diagonal.
Let $S = $ ACGUUACGUU. Let's write the comparison matrix.
\begin{table}
\includegraphics{./figures/part1/comparison_matrix_repetitions.pdf}
\caption{Comparison matrix for $seq = $``ACGUUACGUUGUU"}
\end{table}
\begin{algorithm}
\caption{Construct a comparison matrix}
\begin{algorithmic}[1]
\Function{ComparisonMatrix}{$S$: Array($n$)}
\State $M \gets $ Array($n$, $n$)
\For{($i = 0$; $i < n$; $i++$)}
\For{$j = 0$; $j < n$; $j++$}
\If {$S[i] = S[j]$}
\State $M[i][j] = 1$
\Else
\State $M[i][j] = 0$
\EndIf
\EndFor
\EndFor
\State \Return $M$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Construct the top half of a comparison matrix}
\begin{algorithmic}[1]
\Function{ComparisonMatrix}{$S$: Array($n$)}
\State $M \gets$ Array($n$,$n$)
\For{($i = 0$; $i < n$; $i++$)}
\For{j=i; j < n; j++}
\If {S[i] = S[j]}
\State M[i][j] = 1
\Else
\State M[i][j] = 0
\EndIf
\EndFor
\EndFor
\State \Return M
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Find repetitions (with a set of visited segments)}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start and end positions for repeated sequences}
\State $M = $ \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\State $visited = \{\}$
\For {($i_{start} = 0$; $i_{start} < n$; $i_{start}++$)}
\For {($j_{start} = i_{start}+1$; $j_{start} < n$; $j_{start}++$)}
\If{$M[i_{start}][j_{start}] = 1$ and $(i_{start}, j_{start}) \notin visited$}
\State $i = i_{start}$
\State $j = j_{start}$
\While {$M[i][j] = 1$}
\State $i++$
\State $j++$
\State $visited = visited \cup \{(i, j)\}$
\EndWhile
\State $pos = pos \cup \{(i_{start}, i), (j_{start},j)\}$
\EndIf
\EndFor
\EndFor
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Find repetitions with an exploration of diagonals}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start and end positions for repeted sequences}
\State $M$ = \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\For {($diag = 1$; $diag < n$; $diag++$)}
\State $j = diag$
\State $i = 0$
\While {$i < n$ and $j < n$}
\If {$M[i][j] = 1$}
\State $i_{start} = i$
\State $j_{start} = j$
\While {$i < n$ and $j < n$ and $M[i][j] = 1$}
\State i++
\State j++
\EndWhile
\State $pos = pos \cup \{((i_{start},i-1),(j_{start},j-1))\}$
\EndIf
\State $i++$
\State $j++$
\State
\EndWhile
\EndFor
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Find repetitions with an exploration of diagonals, without nested while}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start positions for repeted sequences and match length}
\State $M$ = \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\For {($diag = 1$; $diag < n$; $diag++$)}
\State $j = diag$
\State $i = 0$
\State $l = 0$
\While {$i < n$ and $j < n$}
\If {$M[i][j] = 1$}
\State $l++$
\Else
\If {$l > 0$}
\State $pos = pos \cup \{(i-l,j-l,l)\}$
\State $l = 0$
\EndIf
\EndIf
\State $i++$
\State $j++$
\EndWhile
\If {$l > 0$}
\State $pos = pos \cup \{((i-l,j-l,l))\}$
\EndIf
\EndFor
\State \Return $pos$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Find repetitions}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start and end positions for repeted sequences}
\State $M$ = \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\For {$i_{start} = 0$; $i_{start} < n$; $i_{start}++$}
\For {$j_{start} = i_{start}+1$; $j_{start} < n$; $j_{start}++$}
\If{$M[i_{start}][j_{start}] = 1$}
\State $i = i_{start}$
\State $j = j_{start}$
\While {$M[i][j] = 1$}
\State $M[i][j] = 0$ \Comment{Ensure that the segment is not explored again}
\State $i++$
\State $j++$
\EndWhile
\State $pos = pos \cup \{((i_{start}, i-1), (j_{start},j-1))\}$
\EndIf
\EndFor
\EndFor
\EndFunction
\end{algorithmic}
\end{algorithm}
\section{Automata}
An automaton is a tuple $\langle S, s_{0}, T, \Sigma,f\rangle$
\begin{itemize}
\item $S$ the set of states
\item $s_{0}$ the initial state
\item $T$ the set of terminal states
\item $\Sigma$ the alphabet
\item $f$ the transition function $f: (s_{1}, c) \to s_{2}$
\end{itemize}
\paragraph{Example} Given the language $L$ on the alphabet $\Sigma = \{A, C, T\}$, $L = \{A^{*}, CTT, CA^{*}\}$
\begin{definition}[Deterministic automaton]
An automaton is deterministic, if for each couple $(p, a) \in S \times \Sigma$ it exists at most a state $q$ such as $f(p, q) = q$
\end{definition}
\begin{definition}[Complete automaton]
An automaton is complete, if for each couple $(p, a) \in S \times \Sigma$ it exists at least a state $q$ such as $f(p, q) = q$.
\end{definition}
\begin{algorithm}
\caption{Check wether a word belong to a language for which we have an automaton}
\begin{algorithmic}[1]
\Function{WordInLanguage}{$W$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma,f \rangle$}
\Returns{A Boolean valued to \True{} if the word is recognized by the language automaton}
\State $s \gets s_{0}$
\State $i \gets 0$
\While {$i < n$}
\State $a \gets W[i]$
\If {$\exists f(s, a)$}
\State $s \gets f(s, a)$
\Else
\State \Return \False
\EndIf
\State i++
\EndWhile
\If {$s \in T$}
\State \Return \True
\Else
\State \Return \False
\EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}
\subsection{Suffix Automaton}
Let $S = $ AACTACT
A suffix automata recognize all suffix of a given sequence.
The suffix language of $S$ is $\{S, ACTACT, CTACT, TACT, ACT, CT, T\}$.
\begin{figure}
\centering
\includegraphics{./figures/part1/minimal_suffix_automaton_exercise.pdf}
\caption{Suffix automaton for $S = $ AACTACT}
\end{figure}
\begin{figure}
\centering
\includegraphics{./figures/part1/minimal_suffix_automaton_exercise_bis.pdf}
\caption{Suffix automaton for $S = $ TCATCATT}
\end{figure}
\begin{algorithm}
\caption{Check if a sequences matches a motif, from a suffix automaton $\mathcal{O}(m)$, built from the automaton}
\begin{algorithmic}[1]
\Function{CheckMotifInSuffixAutomaton}{$W$: Array($m$), $A$: $\langle S, s_{0}, T, \Sigma,f \rangle$}
\Returns{Boolean valued to \True{} if the motif is in the sequence}
\State $s \gets s_{0}$
\State $i \gets 0$
\While {$i < m$ and $\exists f(s, W[i])$}
\State $s \gets f(s, W[i])$
\State $i++$
\EndWhile
\If {$i=n$}
\State \Return \True
\Else
\State \Return \False
\EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}
The complexity of the pattern matching algorithm is $\mathcal{O}(n + m)$, because building the automaton is $\mathcal{O}(m)$
\subsection{Automata for motif search}
Let $M$ be a motif $M = $ ACAT.
\begin{figure}
\centering
\includegraphics{./figures/part1/motif_search_automaton.pdf}
\caption{Motif search automaton for $M = $ ACAT}
\end{figure}
The alphabet of motif is the same as the alphabet of the sequence.
The search automaton is complete.
If the there exists a letter $c$ in the sequence that is not
in the motif alphabet, we can make a virtual transition from
each state to the initial state whenever we encounter an unknown letter.
\begin{algorithm}
\caption{Search a motif in a sequence with an automaton}
\begin{algorithmic}[1]
\Function{SearchMotif}{$S$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma, f \rangle$, $P$: Array($m$)}
\Returns{A set of positions where the motif has been found}
\State $s \gets s_0$
\State $i \gets 0$
\State $pos \gets \{\}$
\While {$i < n$} % $\exists f(s, S[i])$ We assume $S$ and $P$ are formed on the same alphabet, so we could remove the second check, as $A$ is complete
\If {$s \in T$}
\State $pos \gets pos \cup \{ i - m \}$
\EndIf
\State $s \gets f(s, S[i])$
\State $i++$
\EndWhile
\State \Return $pos$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Check if the a motif automaton recognizes only the prefix of size $m-1$ of a motif $P$ of size $m$ }
\begin{algorithmic}[1]
\Function{SearchMotifLastPrefix}{$S$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma, f \rangle$, $P$: Array($m$)}
\Returns{A set of positions where the motif has been found}
\State $s \gets s_0$
\State $i \gets 0$
\State $T_{new} \gets \{\}$
\For {$s \in S$}
\For {$a \in \Sigma$}
\For {$t \in T$}
\If {$\exists f(s, a)$ and $f(s, a) = t$}
\State $T_{new} \gets T_{new} \cup s$
\EndIf
\EndFor
\EndFor
\EndFor
\While {$i < n$}
\If {$s \in T_{new}$}
\State \Return \True
\EndIf
\State $s \gets f(s, S[i])$
\State $i++$
\EndWhile
\State \Return \False
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Check if the a motif automaton recognizes only the prefix of size $m-1$ of a motif $P$ of size $m$, knowing the sequence of the motif}
\begin{algorithmic}[1]
\Function{SearchMotifLastPrefix}{$S$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma, f \rangle$, $P$: Array($m$)}
\Returns{A set of positions where the motif has been found}
\State $s \gets s_0$
\State $i \gets 0$
\While {$i < n$ and $f(s, P[m-1]) \notin T$}
\State $s \gets f(s, S[i])$
\State $i++$
\EndWhile
\If{$f(s, P[m-1]) \in T$}
\State \Return \True
\Else
\State \Return \False
\EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}

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@ -1,52 +1,27 @@
\chapter{Matrices}
Let $S_{1}$ and $S_{2}$ be two sequences.
$S_{1} = $ ACGUUCC
$S_{2} = $ GUU
\begin{table}
\centering
\begin{tabular}{c|ccccccc}
& A & C & G & U & U & C & C \\
\hline
G & 0 & 0 & 1 & 0 & 0 & 0 & 0 \\
U & 0 & 0 & 0 & 1 & 1 & 0 & 0 \\
U & 0 & 0 & 0 & 1 & 1 & 0 & 0
\end{tabular}
\caption{Comparison matrix}
\end{table}
Let $n = |S_{1}|$, $m = |S_{2}|$
The complexity of this algorithm is $\mathcal{O}(n \cdot m)$ to build the matrix, and it requires also to find the diagonals and thus it is a bit less efficient than the \autoref{alg:naive-motif-matching}.
To find repetitions, we can use a comparison matrix with a single sequence against itself. A repetition would appear as a diagonal of ones, not on the main diagonal.
Let $S = $ ACGUUACGUU. Let's write the comparison matrix.
\begin{table}
\includegraphics{./figures/part1/comparison_matrix_repetitions.pdf}
\caption{Comparison matrix for $seq = $``ACGUUACGUUGUU"}
\end{table}
\chapter{Longest common subsequence}
Let $S_{1} = \text{ATCTGAT}$ and $S_{2} = \text{TGCATA}$.
In this case the longest common subsequence of $S_{1}$ and $S_{2}$ is $TCTA$.
\begin{algorithm}
\caption{Construct a comparison matrix}
\caption{Construct a longest common subsequence matrix}
\begin{algorithmic}[1]
\Function{ComparisonMatrix}{$S$: Array($n$)}
\State $M \gets $ Array($n$, $n$)
\For{($i = 0$; $i < n$; $i++$)}
\For{$j = 0$; $j < n$; $j++$}
\If {$S[i] = S[j]$}
\State $M[i][j] = 1$
\Else
\State $M[i][j] = 0$
\EndIf
\EndFor
\Function{LCSQ\_Matrix}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M \gets $ Array($m+1$, $n+1$)
\For{($i = 0$; $i < n+1$; $i++$)}
\For{$j = 0$; $j < m+1$; $j++$}
\If {$i = 0$ or $j = 0$}
\State $M[i][j] = 0$
\Else
\If {$S_{1}[i] = S_{2}[j]$}
\State $match = M[i-1][j-1] + 1$
\Else
\State $match = M[i-1][j-1]$
\EndIf
\State $gap_{1} = M[i-1][j]$
\State $gap_{2} = M[i][j-1]$
\State $M[i][j] = \max \{ match, gap_{1}, gap_{2}\}$
\EndIf
\EndFor
\EndFor
\State \Return $M$
\EndFunction
@ -54,228 +29,88 @@ Let $S = $ ACGUUACGUU. Let's write the comparison matrix.
\end{algorithm}
\begin{algorithm}
\caption{Construct the top half of a comparison matrix}
\caption{Construct a longest common subsequence matrix keeping the path in memory}
\begin{algorithmic}[1]
\Function{ComparisonMatrix}{$S$: Array($n$)}
\State $M \gets$ Array($n$,$n$)
\For{($i = 0$; $i < n$; $i++$)}
\For{j=i; j < n; j++}
\If {S[i] = S[j]}
\State M[i][j] = 1
\Function{LCSQ\_Matrix\_Path}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M \gets $ Array($m+1$, $n+1$)
\State $P \gets $ Array($m+1$, $n+1$)
\For {($i = 0$; $i < n+1$, $i++$)}
\State $M[i][0] \gets 0$
\EndFor
\For {($j = 0$; $j < m+1$; $j+$)}
\State $M[0][j] \gets 0$
\EndFor
\For{($i = 1$; $i < n+1$; $i++$)}
\For{($j = 1$; $j < m+1$; $j++$)}
\If {$i = 1$ or $j = 0$}
\State $M[i][j] = 0$
\Else
\State M[i][j] = 0
\If {$S_{1}[i-1] = S_{2}[j-1]$}
\State $M[i][j] \gets M[i-1][j-1] + 1$
\State $P[i][j] \gets '\nwarrow'$
\ElsIf {$M[i][j-1] \geq M[i-1][j]$}
\State $M[i][j] \gets M[i][j-1]$
\State $P[i][j] \gets '\leftarrow'$
\Else
\State $M[i][j] \gets M[i-1][j]$
\State $P[i][j] \gets '\downarrow'$
\EndIf
\EndIf
\EndFor
\EndFor
\State \Return M
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Find repetitions (with a set of visited segments)}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start and end positions for repeated sequences}
\State $M = $ \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\State $visited = \{\}$
\For {($i_{start} = 0$; $i_{start} < n$; $i_{start}++$)}
\For {($j_{start} = i_{start}+1$; $j_{start} < n$; $j_{start}++$)}
\If{$M[i_{start}][j_{start}] = 1$ and $(i_{start}, j_{start}) \notin visited$}
\State $i = i_{start}$
\State $j = j_{start}$
\While {$M[i][j] = 1$}
\State $i++$
\State $j++$
\State $visited = visited \cup \{(i, j)\}$
\EndWhile
\State $pos = pos \cup \{(i_{start}, i), (j_{start},j)\}$
\EndIf
\EndFor
\EndFor
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Find repetitions with an exploration of diagonals}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start and end positions for repeted sequences}
\State $M$ = \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\For {($diag = 1$; $diag < n$; $diag++$)}
\State $j = diag$
\State $i = 0$
\While {$i < n$ and $j < n$}
\If {$M[i][j] = 1$}
\State $i_{start} = i$
\State $j_{start} = j$
\While {$i < n$ and $j < n$ and $M[i][j] = 1$}
\State i++
\State j++
\EndWhile
\State $pos = pos \cup \{((i_{start},i-1),(j_{start},j-1))\}$
\EndIf
\State $i++$
\State $j++$
\State
\EndWhile
\EndFor
\State \Return $M, P$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Find repetitions with an exploration of diagonals, without nested while}
\caption{Backtrack the longest common subsequence}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start positions for repeted sequences and match length}
\State $M$ = \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\For {($diag = 1$; $diag < n$; $diag++$)}
\State $j = diag$
\State $i = 0$
\State $l = 0$
\While {$i < n$ and $j < n$}
\If {$M[i][j] = 1$}
\State $l++$
\Else
\If {$l > 0$}
\State $pos = pos \cup \{(i-l,j-l,l)\}$
\State $l = 0$
\EndIf
\EndIf
\State $i++$
\State $j++$
\Function{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $L \gets Array(M[n][m])$
\State $k \gets 0$
\State $i \gets n$
\State $j \gets m$
\While{$i > 0$ and $j > 0$}
\If {$P[i][j] = '\nwarrow' $}
\State $L[k] \gets S_{1}[i]$
\State $i--$
\State $j--$
\State $k++$
\ElsIf {$P[i][j] = '\leftarrow'$}
\State $j--$
\Else
\State $i--$
\EndIf
\EndWhile
\If {$l > 0$}
\State $pos = pos \cup \{((i-l,j-l,l))\}$
\EndIf
\EndFor
\State \Return $pos$
\State \Return $L$
\EndFunction
\end{algorithmic}
\end{algorithm}
\iffalse
\begin{algorithm}
\caption{Recursive reconstruction of the longest common subsequence}
\begin{algorithmic}[1]
\Procedure{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $i \gets n$
\State $j \gets m$
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j$}
\EndProcedure
\begin{algorithm}
\caption{Find repetitions}
\begin{algorithmic}[1]
\Function{FindRepetions}{$S$: Array($n$)}
\Returns{A list of start and end positions for repeted sequences}
\State $M$ = \Call{ComparisonMatrix}{S}
\State $pos = \{\}$
\For {$i_{start} = 0$; $i_{start} < n$; $i_{start}++$}
\For {$j_{start} = i_{start}+1$; $j_{start} < n$; $j_{start}++$}
\If{$M[i_{start}][j_{start}] = 1$}
\State $i = i_{start}$
\State $j = j_{start}$
\While {$M[i][j] = 1$}
\State $M[i][j] = 0$ \Comment{Ensure that the segment is not explored again}
\State $i++$
\State $j++$
\EndWhile
\State $pos = pos \cup \{((i_{start}, i-1), (j_{start},j-1))\}$
\EndIf
\EndFor
\EndFor
\EndFunction
\end{algorithmic}
\end{algorithm}
\section{Automata}
An automaton is a tuple $\langle S, s_{0}, T, \Sigma,f\rangle$
\begin{itemize}
\item $S$ the set of states
\item $s_{0}$ the initial state
\item $T$ the set of terminal states
\item $\Sigma$ the alphabet
\item $f$ the transition function $f: (s_{1}, c) \to s_{2}$
\end{itemize}
\paragraph{Example} Given the language $L$ on the alphabet $\Sigma = \{A, C, T\}$, $L = \{A^{*}, CTT, CA^{*}\}$
\begin{definition}[Deterministic automaton]
An automaton is deterministic, if for each couple $(p, a) \in S \times \Sigma$ it exists at most a state $q$ such as $f(p, q) = q$
\end{definition}
\begin{definition}[Complete automaton]
An automaton is complete, if for each couple $(p, a) \in S \times \Sigma$ it exists at least a state $q$ such as $f(p, q) = q$.
\end{definition}
\begin{algorithm}
\caption{Check wether a word belong to a language for which we have an automaton}
\begin{algorithmic}[1]
\Function{WordInLanguage}{$W$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma,f \rangle$}
\Returns{A Boolean valued to \True{} if the word is recognized by the language automaton}
\State $s \gets s_{0}$
\State $i \gets 0$
\While {$i < n$}
\State $a \gets W[i]$
\If {$\exists f(s, a)$}
\State $s \gets f(s, a)$
\Else
\State \Return \False
\EndIf
\State i++
\EndWhile
\If {$s \in T$}
\State \Return \True
\Else
\State \Return \False
\EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}
\section{Suffix Automaton}
Let $S = $ AACTACT
A suffix automata recognize all suffix of a given sequence.
The suffix language of $S$ is $\{S, ACTACT, CTACT, TACT, ACT, CT, T\}$.
\begin{figure}
\centering
\includegraphics{./figures/part1/minimal_suffix_automaton_exercise.pdf}
\caption{Suffix automaton for $S = $ AACTACT}
\end{figure}
\begin{figure}
\centering
\includegraphics{./figures/part1/minimal_suffix_automaton_exercise_bis.pdf}
\caption{Suffix automaton for $S = $ TCATCATT}
\end{figure}
\begin{algorithm}
\caption{Check if a sequences matches a motif, from a suffix automaton $\mathcal{O}(m)$, built from the automaton}
\begin{algorithmic}[1]
\Function{CheckMotifInSuffixAutomaton}{$W$: Array($m$), $A$: $\langle S, s_{0}, T, \Sigma,f \rangle$}
\Returns{Boolean valued to \True{} if the motif is in the sequence}
\State $s \gets s_{0}$
\State $i \gets 0$
\While {$i < m$ and $\exists f(s, W[i])$}
\State $s \gets f(s, W[i])$
\State $i++$
\EndWhile
\If {$i=n$}
\State \Return \True
\Else
\State \Return \False
\EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}
The complexity of the pattern matching algorithm is $\mathcal{O}(n + m)$, because building the automaton is $\mathcal{O}(m)$
\Procedure{Aux}{$P$: Array($n+1$, $m+1$), $S_{1}$: Array($n$), $i$, $j$}
\If {$P[i][j] = '\nwarrow' $}
\State $l \gets S_{1}[i]$
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j-1$}
\State \texttt{print}($l$)
\ElsIf {$P[i][j] = '\leftarrow'$}
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j-1$}
\Else
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j$}
\EndIf
\EndProcedure
\end{algorithmic}
\end{algorithm}
\fi

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@ -1,84 +0,0 @@
\chapter{Automata for motif search}
Let $M$ be a motif $M = $ ACAT.
\begin{figure}
\centering
\includegraphics{./figures/part1/motif_search_automaton.pdf}
\caption{Motif search automaton for $M = $ ACAT}
\end{figure}
The alphabet of motif is the same as the alphabet of the sequence.
The search automaton is complete.
If the there exists a letter $c$ in the sequence that is not
in the motif alphabet, we can make a virtual transition from
each state to the initial state whenever we encounter an unknown letter.
\begin{algorithm}
\caption{Search a motif in a sequence with an automaton}
\begin{algorithmic}[1]
\Function{SearchMotif}{$S$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma, f \rangle$, $P$: Array($m$)}
\Returns{A set of positions where the motif has been found}
\State $s \gets s_0$
\State $i \gets 0$
\State $pos \gets \{\}$
\While {$i < n$} % $\exists f(s, S[i])$ We assume $S$ and $P$ are formed on the same alphabet, so we could remove the second check, as $A$ is complete
\If {$s \in T$}
\State $pos \gets pos \cup \{ i - m \}$
\EndIf
\State $s \gets f(s, S[i])$
\State $i++$
\EndWhile
\State \Return $pos$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Check if the a motif automaton recognizes only the prefix of size $m-1$ of a motif $P$ of size $m$ }
\begin{algorithmic}[1]
\Function{SearchMotifLastPrefix}{$S$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma, f \rangle$, $P$: Array($m$)}
\Returns{A set of positions where the motif has been found}
\State $s \gets s_0$
\State $i \gets 0$
\State $T_{new} \gets \{\}$
\For {$s \in S$}
\For {$a \in \Sigma$}
\For {$t \in T$}
\If {$\exists f(s, a)$ and $f(s, a) = t$}
\State $T_{new} \gets T_{new} \cup s$
\EndIf
\EndFor
\EndFor
\EndFor
\While {$i < n$}
\If {$s \in T_{new}$}
\State \Return \True
\EndIf
\State $s \gets f(s, S[i])$
\State $i++$
\EndWhile
\State \Return \False
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Check if the a motif automaton recognizes only the prefix of size $m-1$ of a motif $P$ of size $m$, knowing the sequence of the motif}
\begin{algorithmic}[1]
\Function{SearchMotifLastPrefix}{$S$: Array($n$), $A$: $\langle S, s_{0}, T, \Sigma, f \rangle$, $P$: Array($m$)}
\Returns{A set of positions where the motif has been found}
\State $s \gets s_0$
\State $i \gets 0$
\While {$i < n$ and $f(s, P[m-1]) \notin T$}
\State $s \gets f(s, S[i])$
\State $i++$
\EndWhile
\If{$f(s, P[m-1]) \in T$}
\State \Return \True
\Else
\State \Return \False
\EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}

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@ -1,116 +0,0 @@
\chapter{Longest common subsequence}
Let $S_{1} = \text{ATCTGAT}$ and $S_{2} = \text{TGCATA}$.
In this case the longest common subsequence of $S_{1}$ and $S_{2}$ is $TCTA$.
\begin{algorithm}
\caption{Construct a longest common subsequence matrix}
\begin{algorithmic}[1]
\Function{LCSQ\_Matrix}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M \gets $ Array($m+1$, $n+1$)
\For{($i = 0$; $i < n+1$; $i++$)}
\For{$j = 0$; $j < m+1$; $j++$}
\If {$i = 0$ or $j = 0$}
\State $M[i][j] = 0$
\Else
\If {$S_{1}[i] = S_{2}[j]$}
\State $match = M[i-1][j-1] + 1$
\Else
\State $match = M[i-1][j-1]$
\EndIf
\State $gap_{1} = M[i-1][j]$
\State $gap_{2} = M[i][j-1]$
\State $M[i][j] = \max \{ match, gap_{1}, gap_{2}\}$
\EndIf
\EndFor
\EndFor
\State \Return $M$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Construct a longest common subsequence matrix keeping the path in memory}
\begin{algorithmic}[1]
\Function{LCSQ\_Matrix\_Path}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M \gets $ Array($m+1$, $n+1$)
\State $P \gets $ Array($m+1$, $n+1$)
\For {($i = 0$; $i < n+1$, $i++$)}
\State $M[i][0] \gets 0$
\EndFor
\For {($j = 0$; $j < m+1$; $j+$)}
\State $M[0][j] \gets 0$
\EndFor
\For{($i = 1$; $i < n+1$; $i++$)}
\For{($j = 1$; $j < m+1$; $j++$)}
\If {$i = 1$ or $j = 0$}
\State $M[i][j] = 0$
\Else
\If {$S_{1}[i-1] = S_{2}[j-1]$}
\State $M[i][j] \gets M[i-1][j-1] + 1$
\State $P[i][j] \gets '\nwarrow'$
\ElsIf {$M[i][j-1] \geq M[i-1][j]$}
\State $M[i][j] \gets M[i][j-1]$
\State $P[i][j] \gets '\leftarrow'$
\Else
\State $M[i][j] \gets M[i-1][j]$
\State $P[i][j] \gets '\downarrow'$
\EndIf
\EndFor
\EndFor
\State \Return $M, P$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Backtrack the longest common subsequence}
\begin{algorithmic}[1]
\Function{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $L \gets Array(M[n][m])$
\State $k \gets 0$
\State $i \gets n$
\State $j \gets m$
\While{$i > 0$ and $j > 0$}
\If {$P[i][j] = '\nwarrow' $}
\State $L[k] \gets S_{1}[i]$
\State $i--$
\State $j--$
\State $k++$
\ElsIf {$P[i][j] = '\leftarrow'$}
\State $j--$
\Else
\State $i--$
\EndIf
\EndWhile
\State \Return $L$
\EndFunction
\end{algorithmic}
\end{algorithm}
\iffalse
\begin{algorithm}
\caption{Recursive reconstruction of the longest common subsequence}
\begin{algorithmic}[1]
\Procedure{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $i \gets n$
\State $j \gets m$
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j$}
\EndProcedure
\Procedure{Aux}{$P$: Array($n+1$, $m+1$), $S_{1}$: Array($n$), $i$, $j$}
\If {$P[i][j] = '\nwarrow' $}
\State $l \gets S_{1}[i]$
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j-1$}
\State \texttt{print}($l$)
\ElsIf {$P[i][j] = '\leftarrow'$}
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j-1$}
\Else
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j$}
\EndIf
\EndProcedure
\end{algorithmic}
\end{algorithm}
\fi

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@ -1,116 +0,0 @@
\chapter{Longest common subsequence}
Let $S_{1} = \text{ATCTGAT}$ and $S_{2} = \text{TGCATA}$.
In this case the longest common subsequence of $S_{1}$ and $S_{2}$ is $TCTA$.
\begin{algorithm}
\caption{Construct a longest common subsequence matrix}
\begin{algorithmic}[1]
\Function{LCSQ\_Matrix}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M \gets $ Array($m+1$, $n+1$)
\For{($i = 0$; $i < n+1$; $i++$)}
\For{$j = 0$; $j < m+1$; $j++$}
\If {$i = 0$ or $j = 0$}
\State $M[i][j] = 0$
\Else
\If {$S_{1}[i] = S_{2}[j]$}
\State $match = M[i-1][j-1] + 1$
\Else
\State $match = M[i-1][j-1]$
\EndIf
\State $gap_{1} = M[i-1][j]$
\State $gap_{2} = M[i][j-1]$
\State $M[i][j] = \max \{ match, gap_{1}, gap_{2}\}$
\EndIf
\EndFor
\EndFor
\State \Return $M$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Construct a longest common subsequence matrix keeping the path in memory}
\begin{algorithmic}[1]
\Function{LCSQ\_Matrix\_Path}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M \gets $ Array($m+1$, $n+1$)
\State $P \gets $ Array($m+1$, $n+1$)
\For {($i = 0$; $i < n+1$, $i++$)}
\State $M[i][0] \gets 0$
\EndFor
\For {($j = 0$; $j < m+1$; $j+$)}
\State $M[0][j] \gets 0$
\EndFor
\For{($i = 1$; $i < n+1$; $i++$)}
\For{($j = 1$; $j < m+1$; $j++$)}
\If {$i = 1$ or $j = 0$}
\State $M[i][j] = 0$
\Else
\If {$S_{1}[i-1] = S_{2}[j-1]$}
\State $M[i][j] \gets M[i-1][j-1] + 1$
\State $P[i][j] \gets '\nwarrow'$
\ElsIf {$M[i][j-1] \geq M[i-1][j]$}
\State $M[i][j] \gets M[i][j-1]$
\State $P[i][j] \gets '\leftarrow'$
\Else
\State $M[i][j] \gets M[i-1][j]$
\State $P[i][j] \gets '\downarrow'$
\EndIf
\EndIf
\EndFor
\EndFor
\State \Return $M, P$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Backtrack the longest common subsequence}
\begin{algorithmic}[1]
\Function{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $L \gets Array(M[n][m])$
\State $k \gets 0$
\State $i \gets n$
\State $j \gets m$
\While{$i > 0$ and $j > 0$}
\If {$P[i][j] = '\nwarrow' $}
\State $L[k] \gets S_{1}[i]$
\State $i--$
\State $j--$
\State $k++$
\ElsIf {$P[i][j] = '\leftarrow'$}
\State $j--$
\Else
\State $i--$
\EndIf
\EndWhile
\State \Return $L$
\EndFunction
\end{algorithmic}
\end{algorithm}
\iffalse
\begin{algorithm}
\caption{Recursive reconstruction of the longest common subsequence}
\begin{algorithmic}[1]
\Procedure{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $i \gets n$
\State $j \gets m$
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j$}
\EndProcedure
\Procedure{Aux}{$P$: Array($n+1$, $m+1$), $S_{1}$: Array($n$), $i$, $j$}
\If {$P[i][j] = '\nwarrow' $}
\State $l \gets S_{1}[i]$
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j-1$}
\State \texttt{print}($l$)
\ElsIf {$P[i][j] = '\leftarrow'$}
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j-1$}
\Else
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j$}
\EndIf
\EndProcedure
\end{algorithmic}
\end{algorithm}
\fi

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@ -1,6 +1,6 @@
\part{Sequence alignment}
\section{Simililarity between sequences}
\chapter{Definitions}
A function $d$ is a distance between two sequences $x$ and $y$ in an alphabet $\Sigma$ if
\begin{itemize}

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@ -1,6 +1,4 @@
\chapter{Section alignment}
\section{Needleman - Wunsch algorithm}
\chapter{Sequence alignment}
\begin{algorithm}
\caption{Needleman-Wunsch Algorithm}
@ -82,7 +80,7 @@
\end{algorithm}
\begin{algorithm}
\caption{Needleman-Wunsch Algorithm (Backtrack) }
\caption{Needleman-Wunsch Algorithm, using proper notation }
\begin{algorithmic}[1]
\Procedure{FillMatrix}{$S_{1}$: Array($m$), $S_{2}$: Array($n$)}
\State $M = $ Array($m+1$, $n+1$)
@ -143,3 +141,82 @@
\State \Call{BacktrackAlignment}{$S_{1}$, $S_{2}$}
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Backtrack a single alignment in a recursive way}
\begin{algorithmic}[1]
\State $S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$),
\Function{BacktrackRecurse}{$i$, $j$}
\If {$i > 0$ and $j > 0$}
\State $substitute = M[i-1][j-1]$
\State $delete = M[i-1][j]$
\State $insert = M[i][j-1]$
\State $min = \min \{ substitute, delete, insert \}$
\If {$substitute = min$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j-1$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ S_{2}[j-1] \end{pmatrix} \circ z$
\ElsIf {$delete = min$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix} \circ z$
\Else
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$}
\State $z = \begin{pmatrix} \varepsilon \\ S_{2}[j-1] \end{pmatrix} \circ z$
\EndIf
\ElsIf {$i > 0$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix} \circ z$
\ElsIf {$j > 0$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix} \circ z$
\Else
\State \Return []
\EndIf
\State \Return $z$
\EndFunction
\Function{Backtrack}{$S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$)}
\State \Return \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $m$, $n$}
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Backtrack all the optimum alignments in a recursive way}
\begin{algorithmic}[1]
\Procedure{BacktrackRecurse}{$S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$), $i$, $j$}
\If {$i > 0$ and $j > 0$}
\State $substitute = M[i-1][j-1]$
\State $delete = M[i-1][j]$
\State $insert = M[i][j-1]$
\State $min = \min \{ substitute, delete, insert \}$
\If {$substitute = min$}
\State $value = \begin{pmatrix} S_{1}[i-1] \\ S_{2}[j-1] \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j-1$, $z'$}
\EndIf
\If {$delete = min$}
\State $value = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$, $z'$}
\EndIf
\If {$insert = min$}
\State $value = \begin{pmatrix} \varepsilon \\ S_{2}[j-1] \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$, $z'$}
\EndIf
\ElsIf {$i > 0$}
\State $value = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$, $z'$}
\ElsIf {$j > 0$}
\State $value = \begin{pmatrix} \varepsilon \\ S_{2}[j-1] \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$, $z'$}
\EndIf
\State \Call{print}{$z$}
\EndProcedure
\Procedure{Backtrack}{$S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$)}
\State \Return \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $m$, $n$, []}
\EndProcedure
\end{algorithmic}
\end{algorithm}

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@ -0,0 +1,64 @@
\part*{Introduction}
\chapter*{Back to basics}
\begin{algorithm}
\caption{Search an element in an array}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element}
\For {($i = 0$; $i < n$; $i++$)}
\If {$A[i] = E$}
\State \Return \True
\EndIf
\EndFor
\State \Return \False
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Search an element in an array using a while loop}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element}
\State $i \gets 0$
\While {$i < n$}
\If {$A[i] = E$}
\State \Return \True
\EndIf
\State $i \gets i + 1$
\EndWhile
\State
\Return
\False
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Search an element in an array using a while loop (bis)}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element}
% \Comment{Version ``preffered" by the professor}
\State $i \gets 0$
\While {$i < n$ and $A[i] \neq E$}
\State $i \gets i + 1$
\EndWhile
\If {$i = n$}
\State
\Return \False \Else \State \Return \True \EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Count the occurrences of an element in an array}
\begin{algorithmic}[1]
\Function{Search}{$A$: Array($n$), $E$: element} \State $c \gets 0$
\For{($i = 0$; $i < n$; $i++$)}
\If {$A[i] = E$}
\State $c \gets c + 1$
\EndIf
\EndFor
\State \Return $c$
\EndFunction
\end{algorithmic}
\end{algorithm}

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@ -9,95 +9,98 @@
\algnewcommand{\NIL}{\textbf{\texttt{NIL}}}
\algnewcommand{\NULL}{\textbf{\texttt{null}}}
\input{definitions.tex}
\usepackage{mathtools}
\begin{document}
\begin{algorithm}
\caption{Construct a longest common subsequence matrix keeping the path in memory}
\caption{Backtrack a single alignment in a recursive way}
\begin{algorithmic}[1]
\Function{LCSQ\_Matrix\_Path}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M \gets $ Array($m+1$, $n+1$)
\State $P \gets $ Array($m+1$, $n+1$)
\For {($i = 0$; $i < n+1$, $i++$)}
\State $M[i][0] \gets 0$
\EndFor
\For {($j = 0$; $j < m+1$; $j+$)}
\State $M[0][j] \gets 0$
\EndFor
\For{($i = 1$; $i < n+1$; $i++$)}
\For{($j = 1$; $j < m+1$; $j++$)}
\If {$i = 1$ or $j = 0$}
\State $M[i][j] = 0$
\Else
\If {$S_{1}[i-1] = S_{2}[j-1]$}
\State $M[i][j] \gets M[i-1][j-1] + 1$
\State $P[i][j] \gets '\nwarrow'$
\ElsIf {$M[i][j-1] \geq M[i-1][j]$}
\State $M[i][j] \gets M[i][j-1]$
\State $P[i][j] \gets '\leftarrow'$
\State $S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$),
\Function{BacktrackRecurse}{$i$, $j$}
\If {$i > 0$ and $j > 0$}
\State $substitute = M[i-1][j-1]$
\State $delete = M[i-1][j]$
\State $insert = M[i][j-1]$
\State $min = \min \{ substitute, delete, insert \}$
\If {$substitute = min$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j-1$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ S_{2}[j-1] \end{pmatrix} \circ z$
\ElsIf {$delete = min$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix} \circ z$
\Else
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$}
\State $z = \begin{pmatrix} \varepsilon \\ S_{2}[j-1] \end{pmatrix} \circ z$
\EndIf
\ElsIf {$i > 0$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix} \circ z$
\ElsIf {$j > 0$}
\State $z = $ \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$}
\State $z = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix} \circ z$
\Else
\State $M[i][j] \gets M[i-1][j]$
\State $P[i][j] \gets '\downarrow'$
\State \Return []
\EndIf
\EndIf
\EndFor
\EndFor
\State \Return $M, P$
\State \Return $z$
\EndFunction
\Function{Backtrack}{$S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$)}
\State \Return \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $m$, $n$}
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Backtrack all the optimum alignments in a recursive way}
\begin{algorithmic}[1]
\Procedure{Recurse}{$S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$), $i$, $j$}
\If {$i > 0$ and $j > 0$}
\State $substitute = M[i-1][j-1]$
\State $delete = M[i-1][j]$
\State $insert = M[i][j-1]$
\State $min = \min \{ substitute, delete, insert \}$
\If {$substitute = min$}
\State $value = \begin{pmatrix} S_{1}[i-1] \\ S_{2}[j-1] \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j-1$, $z'$}
\EndIf
\If {$delete = min$}
\State $value = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$, $z'$}
\EndIf
\If {$insert = min$}
\State $value = \begin{pmatrix} \varepsilon \\ S_{2}[j-1] \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$, $z'$}
\EndIf
\ElsIf {$i > 0$}
\State $value = \begin{pmatrix} S_{1}[i-1] \\ \varepsilon \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i-1$, $j$, $z'$}
\ElsIf {$j > 0$}
\State $value = \begin{pmatrix} \varepsilon \\ S_{2}[j-1] \end{pmatrix}$
\State $z' = value \circ z$
\State \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $i$, $j-1$, $z'$}
\EndIf
\State \Call{print}{$z$}
\EndProcedure
\Procedure{Backtrack}{$S_{1}$: Array($m$), $S_{2}$: Array($n$), $M$: Array($m+1$, $n+1$)}
\State \Return \Call{BacktrackRecurse}{$S_{1}$, $S_{2}$, $M$, $m$, $n$, []}
\EndProcedure
\end{algorithmic}
\end{algorithm}
\end{document}
\end{document}
\iffalse
\begin{algorithm}
\caption{Backtrack the longest common subsequence}
\begin{algorithmic}[1]
\Function{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $L \gets Array(M[n][m])$
\State $k \gets 0$
\State $i \gets n$
\State $j \gets m$
\While{$i > 0$ and $j > 0$}
\If {$P[i][j] = '\nwarrow' $}
\State $L[k] \gets S_{1}[i]$
\State $i--$
\State $j--$
\State $k++$
\ElsIf {$P[i][j] = '\leftarrow'$}
\State $j--$
\Else
\State $i--$
\EndIf
\EndWhile
\State \Return $L$
\EndFunction
\end{algorithmic}
\end{algorithm}
\begin{algorithm}
\caption{Recursive reconstruction of the longest common subsequence}
\begin{algorithmic}[1]
\Procedure{LCSQ}{$S_{1}$: Array($n$), $S_{2}$: Array($m$)}
\State $M, P \gets $ \Call{LCSQ\_Matrix}{$S_{1}$, $S_{2}$}
\State $i \gets n$
\State $j \gets m$
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j$}
\EndProcedure
\Procedure{Aux}{$P$: Array($n+1$, $m+1$), $S_{1}$: Array($n$), $i$, $j$}
\If {$P[i][j] = '\nwarrow' $}
\State $l \gets S_{1}[i]$
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j-1$}
\State \texttt{print}($l$)
\ElsIf {$P[i][j] = '\leftarrow'$}
\State \Call{Aux}{$P$, $S_{1}$, $i$, $j-1$}
\Else
\State \Call{Aux}{$P$, $S_{1}$, $i-1$, $j$}
\EndIf
\EndProcedure
\end{algorithmic}
\end{algorithm}
\Function{AppendToAll}{$value$, $set$}
\Returns {A new set with all elements from $set$ with value appended first to them }
\State $res = \{\}$
\For {$element \in set$}
\State $element = value \circ element$
\State $res = res \cup element$
\EndFor
\State \Return $res$
\EndFunction
\fi
\end{document}
\end{document}