[jboss-svn-commits] JBL Code SVN: r14877 - labs/jbossrules/trunk/documentation/manual/en/Chapter-Solver.
jboss-svn-commits at lists.jboss.org
jboss-svn-commits at lists.jboss.org
Tue Sep 4 16:11:28 EDT 2007
Author: ge0ffrey
Date: 2007-09-04 16:11:27 -0400 (Tue, 04 Sep 2007)
New Revision: 14877
Added:
labs/jbossrules/trunk/documentation/manual/en/Chapter-Solver/Section-What_is_a_Solver.xml
labs/jbossrules/trunk/documentation/manual/en/Chapter-Solver/nQueensDomainDiagram.dia
labs/jbossrules/trunk/documentation/manual/en/Chapter-Solver/nQueensDomainDiagram.png
Log:
What is a solver documentation
Added: labs/jbossrules/trunk/documentation/manual/en/Chapter-Solver/Section-What_is_a_Solver.xml
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--- labs/jbossrules/trunk/documentation/manual/en/Chapter-Solver/Section-What_is_a_Solver.xml (rev 0)
+++ labs/jbossrules/trunk/documentation/manual/en/Chapter-Solver/Section-What_is_a_Solver.xml 2007-09-04 20:11:27 UTC (rev 14877)
@@ -0,0 +1,171 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<section>
+ <title>What is a Solver?</title>
+
+ <section>
+ <title>Introduction</title>
+
+ <para>A solver solves all kinds of planning problems. Good examples of
+ such planning problems include:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Employee shift rostering</para>
+ </listitem>
+
+ <listitem>
+ <para>Freight routing</para>
+ </listitem>
+
+ <listitem>
+ <para>Supply sorting</para>
+ </listitem>
+
+ <listitem>
+ <para>Lesson scheduling</para>
+ </listitem>
+
+ <listitem>
+ <para>Exam scheduling</para>
+ </listitem>
+
+ <listitem>
+ <para><ulink
+ url="http://en.wikipedia.org/wiki/Travelling_salesman_problem">The
+ traveling salesmen problem</ulink></para>
+ </listitem>
+
+ <listitem>
+ <para><ulink url="http://mat.gsia.cmu.edu/TOURN/">The traveling
+ tournament problem</ulink></para>
+ </listitem>
+
+ <listitem>
+ <para>Miss manners too (although drools-solver would solve this
+ differently then the pure drools rule engine example)</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>todo ggg</para>
+ </section>
+
+ <section>
+ <title>Types of solvers</title>
+
+ <para>todo ggg</para>
+ </section>
+
+ <section>
+ <title>The 4 queens example</title>
+
+ <section>
+ <title>Problem statement</title>
+
+ <para>The n queens puzzle is a puzzle with the follow
+ constraints:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Use a chessboard of n rows and n columns.</para>
+ </listitem>
+
+ <listitem>
+ <para>Place n queens on the chessboard.</para>
+ </listitem>
+
+ <listitem>
+ <para>No 2 queens can attack each other. Note that queens can attack
+ horizontally, vertically or diagonally.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>The most common puzzle is for <emphasis>n = 8</emphasis>, so the 8
+ queens puzzle. This manual explains drools-solver using the 4 queens
+ puzzle as it primary example.</para>
+
+ <para>A prosoded solution could be:</para>
+
+ <figure>
+ <title>A wrong solution of the 4 queens puzzle</title>
+
+ <mediaobject>
+ <imageobject>
+ <imagedata align="center"
+ fileref="partiallySolvedNQueens04Explained.svg"
+ format="SVG" />
+ </imageobject>
+
+ <imageobject>
+ <imagedata align="center"
+ fileref="partiallySolvedNQueens04Explained.png"
+ format="PNG" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>The above solution is wrong because queens A1 and B1 can attack
+ each other (as can queens B1 and D1). Removing queen B1 would respect
+ the "no 2 queens can attack each other" constraint, but would break the
+ "place n queens" constraint.</para>
+ </section>
+
+ <section>
+ <title>Solution(s)</title>
+
+ <para>Below is a correct solution:</para>
+
+ <figure>
+ <title>A correct solution of the 4 queens puzzle</title>
+
+ <mediaobject>
+ <imageobject>
+ <imagedata align="center" fileref="solvedNQueens04.svg"
+ format="SVG" />
+ </imageobject>
+
+ <imageobject>
+ <imagedata align="center" fileref="solvedNQueens04.png"
+ format="PNG" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>All the constraints have been met so the solution is correct. Note
+ that most n queens puzzles have multiple correct solutions. The example
+ in this manual focusses on finding a single correct solution, not on
+ finding the number of possible correct solutions for a given n.</para>
+ </section>
+
+ <section>
+ <title>Class diagram</title>
+
+ <para>Using a good domain model will make it easier to understand and
+ solve your problem with drools-solver. The 4 queens example uses this
+ domain model:</para>
+
+ <figure>
+ <title>NQueens domain diagram</title>
+
+ <mediaobject>
+ <imageobject>
+ <imagedata align="center" fileref="nQueensDomainDiagram.png"
+ format="PNG" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>A Queen instance has an <emphasis>x</emphasis> (its column, for
+ example 2 for column B) and a <emphasis>y</emphasis> (its row, for
+ example 3 for row 3). Based on the x and y, the ascending diagonal line
+ as well as the descending diagonal line can be calculated. The x and y
+ indexes start from the upper left corner of the chessboard.</para>
+
+ <para>A singleton NQueens instance contains a list of all Queens. Notice
+ that in the 4 queens example, NQueens.getN() will always return
+ 4.</para>
+
+ <para>You can find the source code of this example (as well as well as
+ several other examples) in the drools-solver src distribution.</para>
+ </section>
+ </section>
+</section>
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