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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Maybe I’m missing something, and you are concerned about something more than just mean-ETL optimization, i.e., using random portfolios or DeOptim due to constraints??? <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>As for the STARR ratio Step 3 is fine, and can also be used for max Sharpe ratio. As long as the efficient frontier is concave both ratios increase until the maximum and then decrease, so a simple line search will work and converge pretty rapidly. I have a placeholder for a max SR section in Chapter 2 and will do soon. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Am I missing something?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Doug<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> gsoc-porta-bounces@lists.r-forge.r-project.org [mailto:gsoc-porta-bounces@lists.r-forge.r-project.org] <b>On Behalf Of </b>Ross Bennett<br><b>Sent:</b> Sunday, October 06, 2013 5:56 PM<br><b>To:</b> PortfolioAnalytics<br><b>Subject:</b> Re: [GSoC-PortA] Mean-mETL objective?<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>It will be nice if there is a simple way to formulate this as an LP problem to maximize mean/ETL. If there is not a simple formulation, one way to approach this would be similar to finding the tangency portfolio on the efficient frontier. Generating a finite number of portfolios along the frontier and finding the portfolio with the highest mean/ETL will find the approximate tangency portfolio and is what I do for the efficient frontier code.<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Step 1: Calculate the minimum ETL portfolio given the constraints. This is the minimum possible mean return.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Step 2: Calculate the maximum return portfolio given the constraints. This is the maximum possible mean return.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Step 3: Increase or decrease the target return constraint and run the optimization.<o:p></o:p></p></div><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Repeat step 3 until we get convergence within a specified tolerance or reach the maximum number of iterations.<o:p></o:p></p></div></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I'm not sure what the right approach or method would be for step 3. Maybe split the frontier in two equal spaces and iteratively shrink the search space until we find a solution. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Am I on the right track here? Any thoughts on how to do step 3?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks,<o:p></o:p></p></div><div><p class=MsoNormal>Ross<o:p></o:p></p></div></div><div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On Sun, Oct 6, 2013 at 8:44 AM, Doug Martin <<a href="mailto:martinrd@comcast.net" target="_blank">martinrd@comcast.net</a>> wrote:<o:p></o:p></p><p class=MsoNormal>Will need to do an in-depth comparison of Rglpk versus Symphony LP (withMIP)<br>solvers.<br><br>I think you mentioned a project for evaluating the various solvers against<br>commonly used benchmark problems? What is the status and timing of that?<o:p></o:p></p><div><p class=MsoNormal><br>Doug<br><br><br><br>-----Original Message-----<br>From: <a href="mailto:gsoc-porta-bounces@lists.r-forge.r-project.org">gsoc-porta-bounces@lists.r-forge.r-project.org</a><br>[mailto:<a href="mailto:gsoc-porta-bounces@lists.r-forge.r-project.org">gsoc-porta-bounces@lists.r-forge.r-project.org</a>] On Behalf Of Brian<br>G. Peterson<o:p></o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'>Sent: Sunday, October 06, 2013 8:19 AM<br>To: <a href="mailto:gsoc-porta@r-forge.wu-wien.ac.at">gsoc-porta@r-forge.wu-wien.ac.at</a><br>Subject: Re: [GSoC-PortA] Mean-mETL objective?<o:p></o:p></p></div><div><div><p class=MsoNormal>On 10/06/2013 10:00 AM, Doug Martin wrote:<br>> P.S. Chapter 4 in the 2nd edition on mean-ETL optimization via LP with<br>> Rglpk, with some nice examples (will send when available). I will also<br>use<br>> this for the MIP examples in an advanced constraints chapter (since we<br>> don't have a QP solver available with MIP capability, unless I can<br>> find time to do a chapter using CPLEX via PortfolioAnalytics via ROI).<br><br>there is also a ROI front end to the MILP Symphony solver.<br><br>I'm not sure iof the Symphony solver includes QP constraints.<br><br>--<br>Brian G. Peterson<br><a href="http://braverock.com/brian/" target="_blank">http://braverock.com/brian/</a><br>Ph: <a href="tel:773-459-4973">773-459-4973</a><br>IM: bgpbraverock<br>_______________________________________________<br>GSoC-PortA mailing list<br><a href="mailto:GSoC-PortA@lists.r-forge.r-project.org">GSoC-PortA@lists.r-forge.r-project.org</a><br><a href="http://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/gsoc-porta" target="_blank">http://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/gsoc-porta</a><br><br>_______________________________________________<br>GSoC-PortA mailing list<br><a href="mailto:GSoC-PortA@lists.r-forge.r-project.org">GSoC-PortA@lists.r-forge.r-project.org</a><br><a href="http://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/gsoc-porta" target="_blank">http://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/gsoc-porta</a><o:p></o:p></p></div></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>