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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<title>Using Pyke</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" href="../stylesheets/pyke.css" type="text/css" />
</head>
<body>
<table id="page-table">
<thead class="head">
<tr id="header1"><th id="header" colspan="3">
&nbsp;
</th></tr>
<tr id="header2">
<th id="crumb-left"></th>
<th id="crumb-line">
<div id="nav">
<ul>
<li><a href="../index.html">Home</a></li>
<li>&gt;</li>
<li>Using Pyke</li>
</ul>
</div>
</th>
<th id="crumb-right"></th>
</tr>
</thead>
<tbody id="body">
<tr id="body-tr">
<td id="left-nav">
<div id="left-nav-div">
<div class="title-nav"><a href="../index.html">Home</a></div><div class="nav-branch">
<div class="normal-nav"><a href="../about_pyke/index.html">About Pyke</a></div>
<div class="normal-nav"><a href="../logic_programming/index.html">Logic Programming</a></div>
<div class="normal-nav"><a href="../knowledge_bases/index.html">Knowledge Bases</a></div>
<div class="normal-nav"><a href="../pyke_syntax/index.html">Pyke Syntax</a></div>
<div class="title-nav"><a href="index.html">Using Pyke</a></div><div class="nav-branch">
<div class="normal-nav"><a href="creating_engine.html">Creating an Engine</a></div>
<div class="normal-nav"><a href="adding_facts.html">Asserting Facts</a></div>
<div class="normal-nav"><a href="proving_goals.html">Proving Goals</a></div>
<div class="normal-nav"><a href="other_functions.html">Other functions</a></div>
</div>
<div class="normal-nav"><a href="../examples.html">Examples</a></div>
<div class="normal-nav"><a href="../PyCon2008-paper.html">PyCon 2008 Paper</a></div>
</div>
</div>
<div id="icons">
<div id="project-page">
<a href="http://sourceforge.net/projects/pyke/">Pyke Project Page</a>
</div>
Please Make a Donation:<br />
<a href="http://sourceforge.net/donate/index.php?group_id=207724">
<img src="http://images.sourceforge.net/images/project-support.jpg"
width="88" height="32" border="0"
alt="Support This Project" /> </a> <br /><br />
Hosted by: <br />
<a href="http://sourceforge.net/projects/pyke">
<img src="http://sflogo.sourceforge.net/sflogo.php?group_id=207724&amp;type=14"
width="150" height="40"
alt="Get Python Knowledge Engine (PyKE) at SourceForge.net. Fast, secure and Free Open Source software downloads" /></a>
</div>
</td>
<td id="main-td">
<div id="main">
<a name="startcontent" id="startcontent"></a>
<div class="document" id="using-pyke">
<h1 class="title">Using Pyke</h1>
<p>This describes how to call Pyke from your Python program.</p>
<div class="section" id="getting-started">
<h2>Getting Started</h2>
<!-- this code is hidden and will set __file__ to the doc/examples directory.
>>> import os
>>> __file__ = \
... os.path.join(os.path.dirname(os.path.dirname(os.getcwd())),
... 'examples') -->
<p>The simplest use of Pyke involves three steps:</p>
<ol class="arabic">
<li><p class="first"><a class="reference external" href="creating_engine.html">Create an engine</a> object.</p>
<pre class="doctest-block">
&gt;&gt;&gt; from pyke import knowledge_engine
</pre>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine = knowledge_engine.engine(__file__)
</pre>
<p>The step compiles the Pyke source files, if out of date, and loads the
<a class="reference external" href="../knowledge_bases/index.html">knowledge bases</a>.</p>
<p>There are three kinds of Pyke source files:</p>
<ol class="arabic simple">
<li><a class="reference external" href="../pyke_syntax/kfb_syntax.html">.kfb files</a> define <a class="reference external" href="../knowledge_bases/fact_bases.html">fact bases</a>, which are compiled into .fbc pickle
files.</li>
<li><a class="reference external" href="../pyke_syntax/krb_syntax/index.html">.krb files</a> define <a class="reference external" href="../knowledge_bases/rule_bases.html">rule bases</a>, which are compiled into 1 to 3 .py
Python source files.</li>
<li><a class="reference external" href="../pyke_syntax/kqb_syntax.html">.kqb files</a> define <a class="reference external" href="../knowledge_bases/question_bases.html">question bases</a>, which are compiled into .qbc
pickle files.</li>
</ol>
</li>
<li><p class="first">Activate <a class="reference external" href="../knowledge_bases/rule_bases.html">rule bases</a>.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.activate('bc_related')
</pre>
<p>You may chose one or more rule bases to activate.</p>
<div class="note">
<p class="first admonition-title">Note</p>
<p class="last">Even if you only have one rule base, you must still activate it.</p>
</div>
<p>This is when the <a class="reference external" href="../logic_programming/rules/forward_chaining.html">forward-chaining rules</a> are run.</p>
</li>
<li><p class="first"><a class="reference external" href="proving_goals.html">Prove</a> <a class="reference external" href="../logic_programming/rules/backward_chaining.html">goal</a>.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.prove_1_goal('bc_related.father_son(bruce, $son, ())')
({'son': 'david'}, None)
</pre>
<p>The goal might be met by simply matching an already known <a class="reference external" href="../knowledge_bases/fact_bases.html#facts">fact</a>, or
through the use of <a class="reference external" href="../logic_programming/rules/backward_chaining.html">backward-chaining rules</a>.</p>
</li>
</ol>
<p>Then if you want to prove another goal, you can just repeat the last step.
In this case, the <a class="reference external" href="../logic_programming/rules/forward_chaining.html">forward-chaining rules</a> are only run once and all goals
operate against the same set of known facts.</p>
<blockquote>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.prove_1_goal('bc_related.father_son(thomas, $son, ())')
({'son': 'tim'}, None)
</pre>
</blockquote>
</div>
<div class="section" id="dynamically-asserting-facts">
<h2>Dynamically Asserting Facts</h2>
<p>To dynamically <a class="reference external" href="adding_facts.html">assert</a> <a class="reference external" href="../knowledge_bases/fact_bases.html#facts">facts</a> within your Python program, a new step is added:</p>
<ol class="arabic">
<li><p class="first">Create an <a class="reference external" href="creating_engine.html">engine</a> object.</p>
<pre class="doctest-block">
&gt;&gt;&gt; from pyke import knowledge_engine
</pre>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine = knowledge_engine.engine(__file__)
</pre>
</li>
<li><p class="first"><a class="reference external" href="adding_facts.html">Assert</a> <a class="reference external" href="../knowledge_bases/fact_bases.html#facts">facts</a>.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.assert_('family2', 'son_of', ('spike', 'david'))
</pre>
<p>These facts must be asserted prior to activating the rule bases so that
they are available to the <a class="reference external" href="../logic_programming/rules/forward_chaining.html">forward-chaining rules</a>.</p>
</li>
<li><p class="first">Activate <a class="reference external" href="../knowledge_bases/rule_bases.html">rule bases</a>.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.activate('bc_related')
</pre>
</li>
<li><p class="first">Prove <a class="reference external" href="../logic_programming/rules/backward_chaining.html">goal</a>.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.prove_1_goal('bc_related.father_son(david, $son, ())')
({'son': 'spike'}, None)
</pre>
</li>
</ol>
</div>
<div class="section" id="using-different-facts-for-different-cases">
<h2>Using Different Facts for Different Cases</h2>
<p>But if you want to prove goals against different sets of facts or using
different rule bases, you need to <a class="reference external" href="index.html#using-different-facts-for-different-cases">reset</a> the Pyke engine:</p>
<ol class="arabic">
<li><p class="first">Create an <tt class="docutils literal"><span class="pre">engine</span></tt> object.</p>
<pre class="doctest-block">
&gt;&gt;&gt; from pyke import knowledge_engine
</pre>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine = knowledge_engine.engine(__file__)
</pre>
</li>
<li><p class="first"><a class="reference external" href="adding_facts.html">Assert</a> <a class="reference external" href="../knowledge_bases/fact_bases.html#facts">facts</a> for first case.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.assert_('family2', 'son_of', ('spike', 'david'))
</pre>
</li>
<li><p class="first">Activate <a class="reference external" href="../knowledge_bases/rule_bases.html">rule bases</a>.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.activate('bc_related')
</pre>
</li>
<li><p class="first">Prove <a class="reference external" href="../logic_programming/rules/backward_chaining.html">goal</a> for first case.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.prove_1_goal('bc_related.father_son(david, $son, ())')
({'son': 'spike'}, None)
</pre>
</li>
<li><p class="first">Reset the Pyke engine.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.reset()
</pre>
<p>This erases all of the case specific facts that you asserted in step 2, as
well as all of the facts asserted by the <a class="reference external" href="../logic_programming/rules/forward_chaining.html">forward-chaining rules</a>.</p>
<p>It also deactivates all of the <a class="reference external" href="../knowledge_bases/rule_bases.html">rule bases</a>, so you'll need to call
activate again after asserting your facts.</p>
</li>
<li><p class="first">Assert <a class="reference external" href="../knowledge_bases/fact_bases.html#facts">facts</a> for second case.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.assert_('family2', 'son_of', ('felix', 'david'))
</pre>
</li>
<li><p class="first">Activate <a class="reference external" href="../knowledge_bases/rule_bases.html">rule bases</a>.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.activate('bc_related')
</pre>
</li>
<li><p class="first">Prove <a class="reference external" href="../logic_programming/rules/backward_chaining.html">goal</a> for second case.</p>
<pre class="doctest-block">
&gt;&gt;&gt; my_engine.prove_1_goal('bc_related.father_son(david, $son, ())')
({'son': 'felix'}, None)
</pre>
</li>
</ol>
<!-- ADD_LINKS MARKER -->
</div>
</div>
<!-- <div id="return-to-top">
<a href="#">Return to Top</a>
</div>
-->
</div>
</td>
<td id="right-nav">
<div id="right-nav-div">
<h3>More:</h3>
<div class="right-item"><a href="creating_engine.html">Creating an Inference Engine Object</a><p>How to create a Pyke <em>inference engine</em> object.</p>
</div>
<div class="right-item"><a href="adding_facts.html">Asserting New Facts</a><p>How to dynamically assert new <em>facts</em> from your Python program.</p>
</div>
<div class="right-item"><a href="proving_goals.html">Proving Goals</a><p>Using Pyke's API to prove goals from your Python program.</p>
</div>
<div class="right-item"><a href="other_functions.html">Other Functions</a><p>Other miscellaneous functions available that you might be interested
in.</p>
</div>
</div>
</td>
</tr>
</tbody>
<tfoot id="foot">
<tr id="foot2">
<td id="copyright" colspan="3">
Copyright &copy; 2007-2009 Bruce Frederiksen
</td>
</tr>
</tfoot>
</table>
<div id="last-modified">
Page last modified
Mon, Mar 08 2010.
</div>
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