<?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>0035-001X</journal-id>
<journal-title><![CDATA[Revista mexicana de física]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fis.]]></abbrev-journal-title>
<issn>0035-001X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0035-001X2012000100009</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[On singular lagrangians and Dirac's method]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Cisneros-Parra]]></surname>
<given-names><![CDATA[J.U.]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Autónoma de San Luis Potosi Facultad de Ciencias ]]></institution>
<addr-line><![CDATA[ San Luis Potosí]]></addr-line>
<country>México</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>02</month>
<year>2012</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>02</month>
<year>2012</year>
</pub-date>
<volume>58</volume>
<numero>1</numero>
<fpage>61</fpage>
<lpage>68</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2012000100009&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2012000100009&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2012000100009&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[We show some instances of singular lagrangians from the classical mechanics of particles and apply Dirac's method for building the canonical equations. We find then the reason for the singularity, and therefore, we get the Hamilton equations with the familiar procedure, that is without the need of Dirac's procedure. Known cases of singular lagrangians in special relativity are also presented, and their non-singular alternatives.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Se presentan algunos lagrangianos singulares del ámbito de la mecánica clásica de partículas, y se les aplica el método de Dirac para construir las ecuaciones canónicas. Se halla la razón de la singularidad, y, con ello, se obtienen las ecuaciones de Hamilton por el camino acostumbrado, esto es, sin necesidad del metodo de Dirac. Se presentan también casos conocidos de lagrangianos singulares en la relatividad especial y sus alternativas no singulares.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Singular lagrangian]]></kwd>
<kwd lng="en"><![CDATA[classical mechanics]]></kwd>
<kwd lng="en"><![CDATA[special relativity]]></kwd>
<kwd lng="es"><![CDATA[Lagrangiano singular]]></kwd>
<kwd lng="es"><![CDATA[mecánica clásica]]></kwd>
<kwd lng="es"><![CDATA[relatividad especial]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="justify"><font face="verdana" size="4">Investigaci&oacute;n</font></p>     <p align="justify"><font face="verdana" size="4">&nbsp;</font></p>     <p align="center"><font face="verdana" size="4"><b>On singular lagrangians and Dirac's method</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>J.U. Cisneros&#150;Parra</b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i>Facultad de Ciencias, Universidad Aut&oacute;noma de San Luis Potosi, Zona Universitaria, San Luis Potos&iacute; 78290, M&eacute;xico.</i></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Recibido el 2 de septiembre de 2011.    <br> Aceptado el 9 de diciembre de 2011.</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2">We show some instances of singular lagrangians from the classical mechanics of particles and apply Dirac's method for building the canonical equations. We find then the reason for the singularity, and therefore, we get the Hamilton equations with the familiar procedure, that is without the need of Dirac's procedure. Known cases of singular lagrangians in special relativity are also presented, and their non&#150;singular alternatives.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords: </b>Singular lagrangian; classical mechanics; special relativity.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>     <p align="justify"><font face="verdana" size="2">Se presentan algunos lagrangianos singulares del &aacute;mbito de la mec&aacute;nica cl&aacute;sica de part&iacute;culas, y se les aplica el m&eacute;todo de Dirac para construir las ecuaciones can&oacute;nicas. Se halla la raz&oacute;n de la singularidad, y, con ello, se obtienen las ecuaciones de Hamilton por el camino acostumbrado, esto es, sin necesidad del metodo de Dirac. Se presentan tambi&eacute;n casos conocidos de lagrangianos singulares en la relatividad especial y sus alternativas no singulares.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Descriptores:</b> Lagrangiano singular; mec&aacute;nica cl&aacute;sica; relatividad especial. </font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">PACS: 45.20.Jj; 11.10.Ef</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v58n1/v58n1a9.pdf" target="_blank">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. P.A.M. Dirac, <i>Canadian Journal of Math. </i><b>2 </b>(1950) 129.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8376421&pid=S0035-001X201200010000900001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">2. P.A.M. Dirac, <i>Proc. Roy. Soc. London A </i><b>246 </b>(1958) 326.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8376423&pid=S0035-001X201200010000900002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">3. P.A.M. Dirac, <i>Lectures on Quantum Mechanics </i>(Belfer Graduate School of Science, Yeshiva University, 1964)</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8376425&pid=S0035-001X201200010000900003&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">4. P. Mittelstaedt, <i>KlassischeMechanik </i>(Bibliographishes Institut, Hochschultaschenbucher Verlag, 1970).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8376426&pid=S0035-001X201200010000900004&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">5. R. Cawley, <i>Phys. Rev. Letters </i><b>42 </b>(1979) 413.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8376428&pid=S0035-001X201200010000900005&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">6. A. Deriglazov, <i>Classical Mechanics Hamiltonian and Lagrangian Formalism </i>(Springer Verlag, 2010).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8376430&pid=S0035-001X201200010000900006&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">7. M. Henneaux, C. Teitelboim, <i>Quantization of Gauge Systems </i>(Princeton University Press, 1991).    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8376432&pid=S0035-001X201200010000900007&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --></font></p>      ]]></body><back>
<ref-list>
<ref id="B1">
<label>1</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Dirac]]></surname>
<given-names><![CDATA[P.A.M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Canadian Journal of Math]]></source>
<year>1950</year>
<volume>2</volume>
<page-range>129</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[Dirac]]></surname>
<given-names><![CDATA[P.A.M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Proc. Roy. Soc. London A]]></source>
<year>1958</year>
<volume>246</volume>
<page-range>326</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[Dirac]]></surname>
<given-names><![CDATA[P.A.M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Lectures on Quantum Mechanics]]></source>
<year>1964</year>
<publisher-name><![CDATA[Belfer Graduate School of Science, Yeshiva University]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B4">
<label>4</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Mittelstaedt]]></surname>
<given-names><![CDATA[P]]></given-names>
</name>
</person-group>
<source><![CDATA[KlassischeMechanik]]></source>
<year>1970</year>
<publisher-name><![CDATA[Bibliographishes InstitutHochschultaschenbucher Verlag]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B5">
<label>5</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Cawley]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
</person-group>
<source><![CDATA[Phys. Rev. Letters]]></source>
<year>1979</year>
<volume>42</volume>
<page-range>413</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[Deriglazov]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
</person-group>
<source><![CDATA[Classical Mechanics Hamiltonian and Lagrangian Formalism]]></source>
<year>2010</year>
<publisher-name><![CDATA[Springer Verlag]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B7">
<label>7</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Henneaux]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
<name>
<surname><![CDATA[Teitelboim]]></surname>
<given-names><![CDATA[C]]></given-names>
</name>
</person-group>
<source><![CDATA[Quantization of Gauge System]]></source>
<year>1991</year>
<publisher-name><![CDATA[Princeton University Press]]></publisher-name>
</nlm-citation>
</ref>
</ref-list>
</back>
</article>
