<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0034-7426</journal-id>
<journal-title><![CDATA[Revista Colombiana de Matemáticas]]></journal-title>
<abbrev-journal-title><![CDATA[Rev.colomb.mat.]]></abbrev-journal-title>
<issn>0034-7426</issn>
<publisher>
<publisher-name><![CDATA[Universidad Nacional de Colombia y Sociedad Colombiana de Matemáticas]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0034-74262014000100005</article-id>
<article-id pub-id-type="doi">10.15446/recolma.v48n1.45196</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Uniform Dimension over Skew PBW Extensions]]></article-title>
<article-title xml:lang="es"><![CDATA[Dimensión uniforme de las extensiones PBW torcidas]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[REYES]]></surname>
<given-names><![CDATA[ARMANDO]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Nacional de Colombia  ]]></institution>
<addr-line><![CDATA[Bogotá ]]></addr-line>
<country>Colombia</country>
</aff>
<pub-date pub-type="pub">
<day>15</day>
<month>06</month>
<year>2014</year>
</pub-date>
<pub-date pub-type="epub">
<day>15</day>
<month>06</month>
<year>2014</year>
</pub-date>
<volume>48</volume>
<numero>1</numero>
<fpage>79</fpage>
<lpage>96</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_arttext&amp;pid=S0034-74262014000100005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_abstract&amp;pid=S0034-74262014000100005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_pdf&amp;pid=S0034-74262014000100005&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[The aim of the present paper is to show that, under some conditions, the uniform dimension of a ring R is the same as the uniform dimension of a skew Poincaré-Birkhoff-Witt extension built on R.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[El propósito de este artículo es mostrar que bajo ciertas condiciones, la dimensión uniforme de un anillo R coincide con la dimensión uniforme de una extensión Poincaré-Birkhoff-Witt torcida de R.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Non-commutative rings]]></kwd>
<kwd lng="en"><![CDATA[Filtered and graded rings]]></kwd>
<kwd lng="en"><![CDATA[PBW extensions]]></kwd>
<kwd lng="en"><![CDATA[Uniform dimension]]></kwd>
<kwd lng="en"><![CDATA[Nonsingular modules]]></kwd>
<kwd lng="es"><![CDATA[Anillos no conmutativos]]></kwd>
<kwd lng="es"><![CDATA[anillos filtrados y graduados]]></kwd>
<kwd lng="es"><![CDATA[extensiones PBW]]></kwd>
<kwd lng="es"><![CDATA[dimensión uniforme]]></kwd>
<kwd lng="es"><![CDATA[módulos no singulares]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[  <font size="2" face="verdana">     <p><a href="http://dx.doi.org/10.15446/recolma.v48n1.45196" target="_blank">http://dx.doi.org/10.15446/recolma.v48n1.45196</a></p>     <p> <b> <font size="4">     <center> Uniform Dimension over Skew <i><b>PBW</b></i> Extensions </center> </font> </b> </p>      <p> <b> <font size="3">     <center> Dimensi&oacute;n uniforme de las extensiones <i><b>PBW</b></i> torcidas </center> </font> </b> </p>      <p>     <center> ARMANDO REYES<sup>1</sup> </center> </p>      <p> <sup>1</sup>Universidad Nacional de Colombia, Bogot&aacute;, Colombia. Email: <a href="mailto:mareyesv@unal.edu.co">mareyesv@unal.edu.co</a>     <br> </p>  <hr size="1">      ]]></body>
<body><![CDATA[<p> <b>     <center> Abstract </center> </b> </p>      <p> The aim of the present paper is to show that, under some conditions, the uniform dimension of a ring <i>R</i> is the same as the uniform dimension of a skew Poincar&eacute;-Birkhoff-Witt extension built on <i>R</i>. </p>      <p> <b> Key words: </b> Non-commutative rings, Filtered and graded rings, <i>PBW</i> extensions, Uniform dimension, Nonsingular modules. </p>  <hr size="1">  <i>2000 Mathematics Subject Classification: 16P40, 16P60, 16W70, 13N10, 16S36.</i>  <hr size="1">      <p> <b>     <center> Resumen </center> </b> </p>      <p> El prop&oacute;sito de este art&iacute;culo es mostrar que bajo ciertas condiciones, la dimensi&oacute;n uniforme de un anillo <i>R</i> coincide con la dimensi&oacute;n uniforme de una extensi&oacute;n Poincar&eacute;-Birkhoff-Witt torcida de <i>R</i>. </p>      <p> <b> Palabras clave: </b> Anillos no conmutativos, anillos filtrados y graduados, extensiones <i>PBW</i>, dimensi&oacute;n uniforme, m&oacute;dulos no singulares. </p>  <hr size="1">      <p> Texto completo disponible en <a href="pdf/rcm/v48n1/v48n1a05.pdf">PDF</a> </p>  <hr size="1">      <p> <b> <font size="3"> References </font> </b> </p>       ]]></body>
<body><![CDATA[<!-- ref --><p> &#91;1&#93; A. D. Bell and K. R. Goodearl, 'Uniform Rank over Differential Operator Rings and Poincar&eacute;-Birkhoff-Witt extensions', <i>Pacific Journal of Mathematics</i> <i>131</i>, 1 (1988), 13-37.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000023&pid=S0034-7426201400010000500001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <p> &#91;2&#93; C. Gallego and O. Lezama, 'Gr&ouml;bner Bases for Ideals of <i>&sigma;-PBW</i> Extensions', <i>Communications in Algebra</i> <i>39</i>, 1 (2011), 50-75. </p>      <!-- ref --><p> &#91;3&#93; K. R. Goodearl, <i>Nonsingular Rings and Modules</i>, Pure and Applied Mathematics, New York, USA,    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000026&pid=S0034-7426201400010000500003&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> 1976. </p>      <!-- ref --><p> &#91;4&#93; K. R. Goodearl and T. Lenagan, 'Krull Dimension of Differential Operator Rings III: Noncommutative Coeficients', <i>Transactions of the American Mathematical Society</i> <i>275</i>,  (1983), 833-859.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000028&pid=S0034-7426201400010000500004&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;5&#93; P. Grzeszczuk, 'Goldie Dimension of Differential Operator Rings', <i>Communications in Algebra</i> <i>16</i>, 4 (1988), 689-701.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000030&pid=S0034-7426201400010000500005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;6&#93; T. Y. Lam, <i>Lectures on Modules and Rings</i>, Springer-Verlag, Graduate Texts in Mathematics 189, New York, USA,    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000032&pid=S0034-7426201400010000500006&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> 1999. </p>      <!-- ref --><p> &#91;7&#93; A. Leroy and J. Matczuk, 'Goldie Conditions for Ore Extensions over Semiprime Rings', <i>Algebras and Representation Theory</i> <i>8</i>,  (2005), 679-688.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000034&pid=S0034-7426201400010000500007&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;8&#93; O. Lezama and A. Reyes, 'Some Homological Properties of Skew PBW Extensions', <i>Communications in Algebra</i> <i>42</i>,  (2014), 1200-1230.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000036&pid=S0034-7426201400010000500008&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;9&#93; J. Matczuk, 'Goldie Rank of Ore Extensions', <i>Communications in Algebra</i> <i>23</i>,  (1995), 1455-1471.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000038&pid=S0034-7426201400010000500009&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;10&#93; J. McConnell and C. Robson, <i>Non-commutative Noetherian Rings, with the Cooperation of L. W. Small.</i>, 2 edn, Graduate Studies in Mathematics. 30. American Mathematical Society (AMS), Providence, USA,    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000040&pid=S0034-7426201400010000500010&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> 2001. </p>      <!-- ref --><p> &#91;11&#93; V. A. Mushrub, 'On the Goldie Dimension of Ore Extensions with Several Variables', <i>Fundamentalnaya i Prikladnaya Matematika</i> <i>7</i>,  (2001), 1107-1121.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000042&pid=S0034-7426201400010000500011&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;12&#93; D. Quinn, 'Embeddings of Differential Operator Rings and Goldie Dimension', <i>Proceedings of the American Mathematical Society</i> <i>102</i>, 1 (1988),    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000044&pid=S0034-7426201400010000500012&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> 9-16. </p>      <p> &#91;13&#93; A. Reyes, Ring and Module Theoretic Properties of <i>&sigma;-PBW</i> Extensions, Ph.D. Thesis, Universidad Nacional de Colombia, 2013a. </p>      <!-- ref --><p> &#91;14&#93; A. Reyes, 'Gelfand-Kirillov Dimension of Skew PBW Extensions', <i>Revista Colombiana de Matem&aacute;ticas</i> <i>47</i>, 1 (2013b), 95-111.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000047&pid=S0034-7426201400010000500014&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;15&#93; R. C. Shock, 'Polynomial Rings over Finite-Dimensional Rings', <i>Pacific Journal of Mathematics</i> <i>42</i>,  (1972), 251-257.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000049&pid=S0034-7426201400010000500015&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>      <!-- ref --><p> &#91;16&#93; G. Sigurdsson, 'Differential Operator Rings whose Prime Factors have Bounded Goldie Dimension', <i>Archiv der Mathematik (Basel)</i> <i>42</i>,  (1984), 348-353.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000051&pid=S0034-7426201400010000500016&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --> </p>  <hr size="1">      ]]></body>
<body><![CDATA[<center> <b>(Recibido en julio de 2013. Aceptado en enero de 2014)</b> </center> <hr size="1">      <p> Este art&iacute;culo se puede citar en <i>LaTeX</i> utilizando la siguiente referencia bibliogr&aacute;fica de <i>BibTeX</i>: </p> <code><font size="2" face="verdana"> @ARTICLE{RCMv48n1a05,    <br>  &nbsp;&nbsp;&nbsp; AUTHOR &nbsp;= {Reyes, Armando},    <br>  &nbsp;&nbsp;&nbsp; TITLE &nbsp; = {{Uniform Dimension over Skew \boldsymbol{PBW} Extensions}},    <br>  &nbsp;&nbsp;&nbsp; JOURNAL = {Revista Colombiana de Matem&aacute;ticas},    <br> &nbsp;&nbsp;&nbsp; YEAR &nbsp;&nbsp; = {2014},    <br> &nbsp;&nbsp;&nbsp; volume &nbsp;= {48},    <br> &nbsp;&nbsp;&nbsp; number &nbsp;= {1},    <br> &nbsp;&nbsp;&nbsp; pages &nbsp; = {79--96}    <br> } </font></code>  <hr size="1"> </font>     ]]></body>
<body><![CDATA[ ]]></body><back>
<ref-list>
<ref id="B1">
<label>1</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Bell]]></surname>
<given-names><![CDATA[A. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Goodearl]]></surname>
<given-names><![CDATA[K. R.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Uniform Rank over Differential Operator Rings and Poincaré-Birkhoff-Witt extensions']]></article-title>
<source><![CDATA[Pacific Journal of Mathematics]]></source>
<year>1988</year>
<volume>131</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>13-37</page-range></nlm-citation>
</ref>
<ref id="B2">
<label>2</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Gallego]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Lezama]]></surname>
<given-names><![CDATA[O.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Gröbner Bases for Ideals of &sigma;-PBW Extensions']]></article-title>
<source><![CDATA[Communications in Algebra]]></source>
<year>2011</year>
<volume>39</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>50-75</page-range></nlm-citation>
</ref>
<ref id="B3">
<label>3</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Goodearl]]></surname>
<given-names><![CDATA[K. R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Nonsingular Rings and Modules]]></source>
<year>1976</year>
<publisher-loc><![CDATA[New York ]]></publisher-loc>
<publisher-name><![CDATA[Pure and Applied Mathematics]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B4">
<label>4</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Goodearl]]></surname>
<given-names><![CDATA[K. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Lenagan]]></surname>
<given-names><![CDATA[T.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Krull Dimension of Differential Operator Rings III: Noncommutative Coeficients']]></article-title>
<source><![CDATA[Transactions of the American Mathematical Society]]></source>
<year>1983</year>
<volume>275</volume>
<page-range>833-859</page-range></nlm-citation>
</ref>
<ref id="B5">
<label>5</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Grzeszczuk]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Goldie Dimension of Differential Operator Rings']]></article-title>
<source><![CDATA[Communications in Algebra]]></source>
<year>1988</year>
<volume>16</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>689-701</page-range></nlm-citation>
</ref>
<ref id="B6">
<label>6</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Lam]]></surname>
<given-names><![CDATA[T. Y.]]></given-names>
</name>
</person-group>
<source><![CDATA[Lectures on Modules and Rings]]></source>
<year>1999</year>
<publisher-loc><![CDATA[New York ]]></publisher-loc>
<publisher-name><![CDATA[Graduate Texts in Mathematics 189]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B7">
<label>7</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Leroy]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Matczuk]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Goldie Conditions for Ore Extensions over Semiprime Rings']]></article-title>
<source><![CDATA[Algebras and Representation Theory]]></source>
<year>2005</year>
<volume>8</volume>
<page-range>679-688</page-range></nlm-citation>
</ref>
<ref id="B8">
<label>8</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Lezama]]></surname>
<given-names><![CDATA[O.]]></given-names>
</name>
<name>
<surname><![CDATA[Reyes]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Some Homological Properties of Skew PBW Extensions']]></article-title>
<source><![CDATA[Communications in Algebra]]></source>
<year>2014</year>
<volume>42</volume>
<page-range>1200-1230</page-range></nlm-citation>
</ref>
<ref id="B9">
<label>9</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Matczuk]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Goldie Rank of Ore Extensions']]></article-title>
<source><![CDATA[Communications in Algebra]]></source>
<year>1995</year>
<volume>23</volume>
<page-range>1455-1471</page-range></nlm-citation>
</ref>
<ref id="B10">
<label>10</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[McConnell]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Robson]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
</person-group>
<source><![CDATA[Non-commutative Noetherian Rings, with the Cooperation of L. W. Small.]]></source>
<year>2001</year>
<edition>2</edition>
<publisher-loc><![CDATA[Providence ]]></publisher-loc>
<publisher-name><![CDATA[Graduate Studies in Mathematics. 30. American Mathematical Society (AMS)]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B11">
<label>11</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Mushrub]]></surname>
<given-names><![CDATA[V. A.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['On the Goldie Dimension of Ore Extensions with Several Variables']]></article-title>
<source><![CDATA[Fundamentalnaya i Prikladnaya Matematika]]></source>
<year>2001</year>
<volume>7</volume>
<page-range>1107-1121</page-range></nlm-citation>
</ref>
<ref id="B12">
<label>12</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Quinn]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Embeddings of Differential Operator Rings and Goldie Dimension']]></article-title>
<source><![CDATA[Proceedings of the American Mathematical Society]]></source>
<year>1988</year>
<volume>102</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>9-16</page-range></nlm-citation>
</ref>
<ref id="B13">
<label>13</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Reyes]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Ring and Module Theoretic Properties of &sigma;-PBW Extensions]]></source>
<year></year>
</nlm-citation>
</ref>
<ref id="B14">
<label>14</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Reyes]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Gelfand-Kirillov Dimension of Skew PBW Extensions']]></article-title>
<source><![CDATA[Revista Colombiana de Matemáticas]]></source>
<year>2013</year>
<month>b</month>
<volume>47</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>95-111</page-range></nlm-citation>
</ref>
<ref id="B15">
<label>15</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Shock]]></surname>
<given-names><![CDATA[R. C.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Polynomial Rings over Finite-Dimensional Rings']]></article-title>
<source><![CDATA[Pacific Journal of Mathematics]]></source>
<year>1972</year>
<volume>42</volume>
<page-range>251-257</page-range></nlm-citation>
</ref>
<ref id="B16">
<label>16</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Sigurdsson]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
</person-group>
<article-title xml:lang="en"><![CDATA['Differential Operator Rings whose Prime Factors have Bounded Goldie Dimension']]></article-title>
<source><![CDATA[Archiv der Mathematik (Basel)]]></source>
<year>1984</year>
<volume>42</volume>
<page-range>348-353</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
