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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html>
<head>
<title>Semantic Guidance in Prover9</title>
</head>
<body>
<h1>Semantic Guidance in Prover9</h1>
Using finite interpretations (models, algebras)
to <i>guide</i> the search for a proof.
<h2>Evaluating a Clause in an Interpretation</h2>
<ul>
<li>If all the symbols in the clause are interpreted,
the clause evaluates to TRUE or to FALSE.
<li>It can be expensive: If the interpretation has
<i>n</i> elements, and the clause has <i>v</i> variables,
there are <i>n<sup>v</sup></i> instances to consider.
</ul>
<h2>Semantic Restrictions on Inference Rules</h2>
(old method)
<ul>
<li>Example: one parent must be false in the interpretation.
<li>Problems:
<ul>
<li>blocks very useful clauses
<li>frequently incompatible with simplification strategies
</ul>
</ul>
<hr>
<h2>Semantic Guidance</h2>
<ul>
<li>Use interpretations to help
<a href="select.html">select the given clause</a>.
<li><a href="semantics.html">Example</a>.
</ul>
<hr>
<h2>Non-standard Uses of Semantic Guidance</h2>
<ul>
<li>Generate a lot of FALSE identities as candidates
to replace a quasi-identity (Kinyon).
</ul>
</body>
</html>
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