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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<div class="document" id="fc-rule-syntax">
<h1 class="title">Fc_rule Syntax</h1>
<div class="section">
<h2><a id="fc-rule" name="fc-rule">Fc_rule</a></h2>
<p><a class="reference" href="../../logic_programming/rules/forward_chaining.html">Forward-chaining</a> rules have three parts:</p>
<ol class="arabic simple">
<li>A unique name.</li>
<li>An optional <a class="reference" href="#foreach-clause">foreach clause</a>.</li>
<li>An <a class="reference" href="#assert-clause">assert clause</a>.</li>
</ol>
<pre class="literal-block">
fc_rule ::= IDENTIFIER NL INDENT
[fc_foreach]
fc_assert
DEINDENT
</pre>
<p>The <tt class="docutils literal"><span class="pre">IDENTIFIER</span></tt> uniquely names this <a class="reference" href="../../logic_programming/rules/index.html">rule</a> and is used as the corresponding
Python function name in the generated &lt;rb_name&gt;_fc.py file.</p>
</div>
<div class="section">
<h2><a id="foreach-clause" name="foreach-clause">Foreach clause</a></h2>
<pre class="literal-block">
fc_foreach ::= 'foreach' NL INDENT
{fc_premise NL}
DEINDENT
fc_premise ::= fact_pattern
| compound_premise
| python_premise
fact_pattern ::= IDENTIFIER '.' IDENTIFIER '(' [{pattern,}] ')'
</pre>
<p>Here are links to the definitions for <a class="reference" href="pattern.html">pattern</a>, <a class="reference" href="compound_premise.html">compound_premise</a> and
<a class="reference" href="python_premise.html">python_premise</a>.</p>
<p>If the <tt class="docutils literal"><span class="pre">foreach</span></tt> clause is omitted, the <a class="reference" href="../../logic_programming/rules/index.html">rule</a> is always fired once.</p>
<p>If the <tt class="docutils literal"><span class="pre">foreach</span></tt> clause is present, the rule is fired for each combination
of true premises.</p>
</div>
<div class="section">
<h2><a id="assert-clause" name="assert-clause">Assert clause</a></h2>
<pre class="literal-block">
fc_assert ::= 'assert' NL INDENT
{assertion NL}
DEINDENT
assertion ::= fact_pattern
| python_statements
</pre>
<p>Here is the link to the definitions of <a class="reference" href="python_premise.html#python-statements">python_statements</a>.</p>
<p>The <tt class="docutils literal"><span class="pre">assert</span></tt> clause lists new <a class="reference" href="../../knowledge_bases/fact_bases.html#facts">facts</a> to assert, and/or Python
statements to execute each time the <a class="reference" href="../../logic_programming/rules/index.html">rule</a> is fired. Each of these may
include <a class="reference" href="pattern.html#pattern-variable">pattern variables</a> which should also appear in the <tt class="docutils literal"><span class="pre">foreach</span></tt>
clause where they are bound to a value. These values will then be substituted
into the facts and Python statements.</p>
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<h3>More:</h3>
<div class="right-item"><a href="fc_rule.html">Fc_rule Syntax</a><p>The syntax of a forward-chaining rule.</p>
</div>
<div class="right-item"><a href="bc_rule.html">Bc_rule Syntax</a><p>The syntax of a backward-chaining rule.</p>
</div>
<div class="right-item"><a href="pattern.html">Pattern Syntax</a><p>The syntax of a pattern used to match data values.</p>
</div>
<div class="right-item"><a href="compound_premise.html">Compound Premise Syntax</a><p>The syntax of compound premises.</p>
</div>
<div class="right-item"><a href="python_premise.html">Python Premise Syntax</a><p>The syntax of a <em>python_premise</em>.</p>
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Copyright &copy; 2007-2009 Bruce Frederiksen
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Page last modified
Mon, Oct 27 2008.
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