/usr/lib/swi-prolog/doc/Manual/varnumbers.html

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<h2 id="sec:varnumbers"><a id="sec:A.32"><span class="sec-nr">A.32</span> <span class="sec-title">library(varnumbers): 
Utilities for numbered terms</span></a></h2>

<p><a id="sec:varnumbers"></a>

<dl class="tags">
<dt class="tag">See also</dt>
<dd>
<a class="pred" href="manipterm.html#numbervars/4">numbervars/4</a>, <a class="pred" href="compare.html#=@=/2">=@=/2</a> 
(<span class="pred-ext">variant/2</span>).
</dd>
<dt class="tag">Compatibility</dt>
<dd>
This library was introduced by Quintus and available in many related 
implementations, although not with exactly the same set of predicates.
</dd>
</dl>

<p>This library provides the inverse functionality of the built-in
<a class="pred" href="manipterm.html#numbervars/3">numbervars/3</a>. 
Note that this library suffers from the known issues that '$VAR'(X) is a 
normal Prolog term and, -unlike the built-in numbervars-, the inverse 
predicates do <i>not</i> process cyclic terms. The following predicate 
is true for any acyclic term that contains no '$VAR'(X),
<code>integer(X)</code> terms and no constraint variables:

<pre class="code">
always_true(X) :-
      copy_term(X, X2),
      numbervars(X),
      varnumbers(X, Copy),
      Copy =@= X2.
</pre>

<dl class="latex">
<dt class="pubdef"><span class="pred-tag">[det]</span><a id="numbervars/1"><strong>numbervars</strong>(<var>+Term</var>)</a></dt>
<dd class="defbody">
Number variables in <var>Term</var> using $VAR(N). Equivalent to
<code>numbervars(Term, 0, _)</code>.

<dl class="tags">
<dt class="tag">See also</dt>
<dd>
<a class="pred" href="manipterm.html#numbervars/3">numbervars/3</a>, <a class="pred" href="manipterm.html#numbervars/4">numbervars/4</a>
</dd>
</dl>

</dd>
<dt class="pubdef"><span class="pred-tag">[det]</span><a id="varnumbers/2"><strong>varnumbers</strong>(<var>+Term, 
-Copy</var>)</a></dt>
<dd class="defbody">
Inverse of <a class="pred" href="varnumbers.html#numbervars/1">numbervars/1</a>. 
Equivalent to <code>varnumbers(Term, 0, Copy)</code>.</dd>
<dt class="pubdef"><span class="pred-tag">[det]</span><a id="varnumbers/3"><strong>varnumbers</strong>(<var>+Term, 
+Start, -Copy</var>)</a></dt>
<dd class="defbody">
Inverse of <a class="pred" href="manipterm.html#numbervars/3">numbervars/3</a>. 
True when <var>Copy</var> is a copy of <var>Term</var> with all 
variables numbered <code>&gt;=</code> <var>Start</var> consistently 
replaced by fresh variables. Variables in <var>Term</var> are <i>shared</i> 
with <var>Copy</var> rather than replaced by fresh variables.

<dl class="tags">
<dt class="tag">Errors</dt>
<dd>
<code>domain_error(acyclic_term, Term)</code> if <var>Term</var> is 
cyclic.
</dd>
<dt class="tag">Compatibility</dt>
<dd>
Quintus, SICStus. Not in YAP version of this library
</dd>
</dl>

</dd>
<dt class="pubdef"><span class="pred-tag">[det]</span><a id="max_var_number/3"><strong>max_var_number</strong>(<var>+Term, 
+Start, -Max</var>)</a></dt>
<dd class="defbody">
True when <var>Max</var> is the max of <var>Start</var> and the highest 
numbered
$VAR(N) term.

<dl class="tags">
<dt class="tag">author</dt>
<dd>
Vitor Santos Costa
</dd>
<dt class="tag">Compatibility</dt>
<dd>
YAP
</dd>
</dl>

</dd>
</dl>

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swi-prolog-nox 6.6.4-2ubuntu1 / usr / lib / swi-prolog / doc / Manual / varnumbers.html
