204 lines
14 KiB
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204 lines
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<table width="100%"><tr><td align="center">/home/caleb/ASDV-Java/Semester 2/Assignments/MP5_CalebFontenot/src/main/java/com/calebfontenot/mp5_calebfontenot/NormalizeDatabase.java</td></tr></table>
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<pre>
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<span class="comment">/*</span>
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<span class="comment"> * Click </span><span class="ST0">nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt</span><span class="comment"> to change this license</span>
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<span class="comment"> * Click </span><span class="ST0">nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java</span><span class="comment"> to edit this template</span>
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<span class="comment"> */</span>
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<span class="literal">package</span> com.calebfontenot.mp5_calebfontenot;
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<span class="comment">/**</span>
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<span class="comment"> *</span>
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<span class="comment"> * </span><span class="comment">@author</span> <span class="comment">caleb</span>
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<span class="comment">*/</span>
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<span class="comment">/*</span>
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<span class="comment"> * To change this license header, choose License Headers in Project Properties.</span>
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<span class="comment"> * To change this template file, choose Tools | Templates</span>
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<span class="comment"> * and open the template in the editor.</span>
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<span class="comment"> */</span>
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<span class="literal">import</span> java.util.ArrayList;
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<span class="comment">/**</span>
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<span class="comment"> *</span>
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<span class="comment"> * </span><span class="comment">@author</span> <span class="comment">ASDV2</span>
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<span class="comment">*/</span>
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<span class="literal">public</span> <span class="literal">class</span> NormalizeDatabase
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{
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<span class="comment">/**</span><span class="comment">Finds</span> <span class="comment">the</span> <span class="comment">closure</span> <span class="comment">of</span> <span class="comment">a</span> <span class="comment">set</span> <span class="comment">of</span> <span class="comment">attributes</span> <span class="comment">given</span> <span class="comment">a</span> <span class="comment">set</span> <span class="comment">of</span> <span class="comment">FDs</span> <span class="comment">of</span> <span class="comment">a</span> <span class="comment">relation</span> <span class="comment">R</span>
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<span class="comment"> * </span>
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<span class="comment"> * </span><span class="comment">@param</span> <span class="ST1">attributes</span> <span class="comment">attributes</span> <span class="comment">to</span> <span class="comment">find</span> <span class="comment">their</span> <span class="comment">closure</span>
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<span class="comment"> * </span><span class="comment">@param</span> <span class="ST1">fds</span> <span class="comment">set</span> <span class="comment">of</span> <span class="comment">FDs</span> <span class="comment">of</span> <span class="comment">relation</span> <span class="comment">R</span>
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<span class="comment"> * </span><span class="comment">@return</span> <span class="comment">the</span> <span class="comment">closure</span> <span class="comment">of</span> <span class="comment">the</span> <span class="comment">parameter</span> <span class="comment">attributes</span><span class="comment">.</span>
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<span class="comment">*/</span>
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<span class="literal">public</span> <span class="literal">static</span> String <span class="ST2">closure</span>(String attributes, ArrayList<FD> fds )
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{
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attributes = attributes.toUpperCase();
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<span class="literal">for</span> (<span class="literal">int</span> j = <span class="number">0</span>; j < fds.size(); ++j)
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{
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FD capitalsFD = <span class="literal">new</span> FD(fds.get(j).getLhs().toUpperCase(),
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fds.get(j).getRhs().toUpperCase());
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fds.set(j, capitalsFD);
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}
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<span class="comment">// 1. Set x+ = x</span>
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String closure = attributes;
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String closurePreveious = attributes;
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<span class="comment">// 2. Starting with x+ apply each FD xF —> y in F where</span>
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<span class="comment">// xF belongs in closure x+ but but the rhs y is not already in x+, to find determined</span>
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<span class="comment">// attributes y</span>
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<span class="comment">// 3. x+ = x+ U y</span>
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<span class="literal">while</span> (<span class="literal">true</span>)
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{
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<span class="literal">for</span> (<span class="literal">int</span> i = <span class="number">0</span>; i < fds.size(); ++i)
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{
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<span class="literal">if</span> (closure.contains(fds.get(i).getRhs()))
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<span class="literal">continue</span>;
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<span class="comment">// if the left hand side of the FD is contained in the closure</span>
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<span class="comment">// then add to the closure the RHS of the FD</span>
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<span class="literal">if</span> (closure.contains(fds.get(i).getLhs()))
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closure += fds.get(i).getRhs();
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}
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<span class="literal">if</span> (closurePreveious.equals(closure))
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<span class="literal">break</span>;
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<span class="literal">else</span>
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closurePreveious = closure;
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}
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<span class="comment">// 4, If y not empty goto (2)</span>
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<span class="comment">// 5. Return x+</span>
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<span class="literal">return</span> closure;
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}
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<span class="comment">/**</span>
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<span class="comment"> * </span><span class="comment">Eliminates</span> <span class="comment">redundant</span> <span class="comment">attributes</span> <span class="comment">from</span> <span class="comment">the</span> <span class="comment">LHS</span> <span class="comment">of</span> <span class="comment">each</span> <span class="comment">FD</span> <span class="comment">of</span> <span class="comment">a</span> <span class="comment">set</span> <span class="comment">of</span> <span class="comment">FDs</span>
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<span class="comment"> * </span><span class="comment">given</span> <span class="comment">as</span> <span class="comment">parameters</span><span class="comment">.</span>
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<span class="comment"> *</span>
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<span class="comment"> * </span><span class="comment">@param</span> <span class="ST1">fds</span> <span class="comment">the</span> <span class="comment">set</span> <span class="comment">of</span> <span class="comment">FDs</span> <span class="comment">to</span> <span class="comment">eliminate</span> <span class="comment">the</span> <span class="comment">redundancy</span>
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<span class="comment"> * </span><span class="comment">@return</span> <span class="comment">and</span> <span class="comment">ArrayList</span> <span class="comment">with</span> <span class="comment">no</span> <span class="comment">redundancy</span> <span class="comment">on</span> <span class="comment">LHS</span> <span class="comment">of</span> <span class="comment">each</span> <span class="comment">FD</span><span class="comment">.</span>
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<span class="comment">*/</span>
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<span class="literal">public</span> <span class="literal">static</span> ArrayList<FD> <span class="ST2">eliminateRedundantAttributes</span>(ArrayList<FD> fds)
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{
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<span class="literal">for</span> (<span class="literal">int</span> j = <span class="number">0</span>; j < fds.size(); ++j)
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{
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<span class="literal">int</span> s = fds.get(j).getLhs().length();
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<span class="literal">if</span> (s < <span class="number">2</span>)
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{
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<span class="literal">continue</span>;
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}
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<span class="literal">else</span>
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{
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String fl = fds.get(j).getLhs().substring(<span class="number">0</span>, <span class="number">1</span>);
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ArrayList<FD> <span class="comment">fFD</span> = <span class="literal">new</span> ArrayList<FD>();
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String s1 = <span class="string">"</span> <span class="string">"</span>;
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<span class="literal">if</span> (fds.get(j).getLhs().length() == <span class="number">2</span>)
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{
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s1 = fds.get(j).getLhs().substring(<span class="number">1</span>);
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<span class="literal">if</span> (<span class="ST3">closure</span>(s1,fds).contains(fl))
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{
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fds.add(<span class="literal">new</span> FD (fds.get(j).getLhs().substring(<span class="number">1</span>, <span class="number">2</span>), fds.get(j).getRhs()));
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fds.remove(j);
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}
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}
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<span class="literal">else</span> <span class="literal">if</span> (fds.get(j).getLhs().charAt(<span class="number">1</span>) == <span class="number">3</span>)
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{
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s1 = fds.get(j).getLhs().substring(<span class="number">1</span>);
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<span class="literal">if</span> (<span class="ST3">closure</span>(s1,fds).contains(fl))
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{
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fds.add(<span class="literal">new</span> FD (fds.get(j).getLhs().substring(<span class="number">1</span>, <span class="number">2</span>), fds.get(j).getRhs()));
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fds.add(<span class="literal">new</span> FD (fds.get(j).getLhs().substring(<span class="number">2</span>, <span class="number">3</span>), fds.get(j).getRhs()));
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fds.remove(j);
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}
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}
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<span class="literal">else</span> <span class="literal">if</span> (fds.get(j).getLhs().charAt(<span class="number">1</span>) == <span class="number">4</span>)
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{
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s1 = fds.get(j).getLhs().substring(<span class="number">1</span>);
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<span class="literal">if</span> (<span class="ST3">closure</span>(s1,fds).contains(fl))
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{
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fds.add(<span class="literal">new</span> FD (fds.get(j).getLhs().substring(<span class="number">1</span>, <span class="number">2</span>), fds.get(j).getRhs()));
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fds.add(<span class="literal">new</span> FD (fds.get(j).getLhs().substring(<span class="number">2</span>, <span class="number">3</span>), fds.get(j).getRhs()));
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fds.add(<span class="literal">new</span> FD (fds.get(j).getLhs().substring(<span class="number">3</span>, <span class="number">4</span>), fds.get(j).getRhs()));
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fds.remove(j);
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}
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}
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<span class="literal">else</span>
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{
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<span class="literal">return</span> fds;
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}
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}
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}
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<span class="literal">return</span> fds;
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}
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<span class="literal">public</span> <span class="literal">static</span> <span class="literal">void</span> <span class="ST2">main</span>(String[] args)
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{
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ArrayList<FD> fds = <span class="literal">new</span> ArrayList<FD>();
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FD fd = <span class="literal">new</span> FD(<span class="string">"</span><span class="string">a</span><span class="string">"</span>, <span class="string">"</span><span class="string">BC</span><span class="string">"</span>);
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FD[] fdDecomposed = fd.decomposeRightHandSide();
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<span class="literal">for</span> (<span class="literal">int</span> i = <span class="number">0</span>; i < fdDecomposed.<span class="ST4">length</span>; ++i)
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{
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fds.add( <span class="literal">new</span> FD(fdDecomposed[i].getLhs(), fdDecomposed[i].getRhs()));
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}
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fds.add(<span class="literal">new</span> FD(<span class="string">"</span><span class="string">B</span><span class="string">"</span>, <span class="string">"</span><span class="string">C</span><span class="string">"</span>));
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fds.add(<span class="literal">new</span> FD(<span class="string">"</span><span class="string">AB</span><span class="string">"</span>, <span class="string">"</span><span class="string">B</span><span class="string">"</span>));
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fds.add(<span class="literal">new</span> FD(<span class="string">"</span><span class="string">C</span><span class="string">"</span>, <span class="string">"</span><span class="string">A</span><span class="string">"</span>));
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System.<span class="ST5">out</span>.println(fds);
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System.<span class="ST5">out</span>.println(<span class="ST3">c</span><span class="ST3">losure</span>(<span class="string">"</span><span class="string">b</span><span class="string">"</span>, fds));
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System.<span class="ST5">out</span>.println(<span class="ST3">e</span><span class="ST3">liminateRedundantAttributes</span>(fds));
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<span class="comment">/* TEST it with </span>
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<span class="comment"> Let F1 = {1. A -> BC </span>
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<span class="comment"> 2. B -> C, </span>
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<span class="comment"> 3. AB -> D }. </span>
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<span class="comment"> Attribute B is extraneous in FD 3 AB -> D</span>
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<span class="comment"> */</span>
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<span class="comment">/*</span>
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<span class="comment"> F2 = { 1. AB -> C, </span>
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<span class="comment"> 2. C -> A, </span>
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<span class="comment"> 3. BC -> D, </span>
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<span class="comment"> 4. ACD -> B, </span>
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<span class="comment"> 5. D -> E, </span>
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<span class="comment"> 6. D -> G, </span>
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<span class="comment"> 7. BE -> C, </span>
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<span class="comment"> 8. CG -> B,</span>
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<span class="comment"> 9. CG -> D, </span>
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<span class="comment"> 10. CE -> A, </span>
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<span class="comment"> 11. CE -> G}</span>
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<span class="comment"> */</span>
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}
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}
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</pre></body>
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