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<h4 class="subsubsection">D.5.8.6 is_reg</h4>
<a name="index-is_005freg"></a>
<p>Procedure from library <code>sing.lib</code> (see <a href="sing_005flib.html#sing_005flib">sing_lib</a>).
</p>
<dl compact="compact">
<dt><strong>Usage:</strong></dt>
<dd><p>is_reg(f,id); f poly, id ideal or module
</p>
</dd>
<dt><strong>Return:</strong></dt>
<dd><p>1 if multiplication with f is injective modulo id, 0 otherwise
</p>
</dd>
<dt><strong>Note:</strong></dt>
<dd><p>let R be the basering and id a submodule of R^n. The procedure checks
injectivity of multiplication with f on R^n/id. The basering may be a
quotient ring
</p>
</dd>
</dl>
<p><strong>Example:</strong>
</p><div class="smallexample">
<pre class="smallexample">LIB &quot;sing.lib&quot;;
ring r  = 32003,(x,y),ds;
ideal i = x8,y8;
ideal j = (x+y)^4;
i       = intersect(i,j);
poly f  = xy;
is_reg(f,i);
&rarr; 0
</pre></div>

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