<div dir="ltr"><div><div class="gmail_default" style="font-family:georgia,serif;font-size:small;color:rgb(0,0,0)"><b>When:         </b>October 31st <b>at <span style="background-color:rgb(255,255,0)">11am CT  </span></b></div><div><div class="gmail_default"><div dir="ltr"><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font color="#000000" face="georgia, serif"> <br><b>Where:</b><b>  </b>      Talk will be given<span style="background-color:rgb(255,255,0)"> </span><span style="background-color:rgb(255,255,0)"><font style="font-weight:bold"><u>live, in-person</u></font><font style="font-weight:bold"> </font></span>at</font></p><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font color="#000000" face="georgia, serif">                       TTIC, 6045 S. Kenwood Avenue</font></p><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font color="#000000" face="georgia, serif">                        5th Floor, Room 530<b>              </b>   </font></p><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font color="#000000" face="georgia, serif"><br></font></p><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="georgia, serif" color="#000000"><b><span class="gmail_default"></span>Virtually:</b>    via Panopto (<a href="https://uchicago.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=12420ed1-85ce-4602-9d3d-b31a00f2af86" target="_blank">Livestream</a>) </font></p><font face="georgia, serif" color="#000000"> <br><b>Who:</b>            Stephen Wright, University of Wisconsin–Madison<br><br><b>Title:</b>            Gradient-Based Methods for Bilevel Optimization</font></div><div dir="ltr"><font face="georgia, serif" color="#000000"><br></font></div><div dir="ltr"><font face="georgia, serif" color="#000000"><b>Abstract: </b>    Bilevel optimization has emerged as a powerful framework across such machine learning applications as reinforcement learning and language model fine-tuning, as well as in game-theoretic modeling. As these problems scale, so too does the need for principled, efficient algorithms that can handle stochasticity and structural complexity.</font></div><div dir="ltr"><font face="georgia, serif" color="#000000">This talk will discuss recent advances in scalable, gradient-based methods for bilevel problems with smooth objectives, where gradients are accessed only through unbiased stochastic oracles. First, we consider the foundational case in which the lower-level problem is strongly convex, and establish non-asymptotic convergence guarantees for finding an epsilon-approximate stationary point.  Second, we explore two active frontiers: (1) extensions to fully nonconvex objectives, including settings with lower-level constraints, and (2) new complexity lower bounds informed by different oracle models. Together, these results form a unified theoretical framework for understanding and designing gradient-based bilevel solvers at scale.<br><br>(Joint work with Jeongyeol Kwon, Dohyun Kwon, Rob Nowak)<br></font><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="georgia, serif" color="#000000"><br></font></p><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="georgia, serif" color="#000000"><br></font></p></div></div><div style=""><div class="gmail_default"><b><font color="#000000" face="georgia, serif">*********************************************************************************************</font></b></div><p class="MsoNormal" style="margin:0in 0in 8pt;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;line-height:15.6933px"><b><i><font color="#000000" face="georgia, serif">Research at TTIC Seminar Series</font></i></b></p><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font color="#000000" face="georgia, serif"> </font></p><div class="gmail_default"><div dir="ltr"><div class="gmail_default"><div dir="ltr"><p class="MsoNormal" style="margin:0in;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="georgia, serif" color="#000000">TTIC is hosting a weekly seminar series presenting the research currently underway at the Institute. Every week a different TTIC faculty member will present their research.  The lectures are intended for students seeking research topics and advisors, and for the general TTIC and University of Chicago communities interested in hearing what their colleagues are up to.</font></p></div></div></div></div></div></div><br clear="all"></div><div><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><b style="background-color:rgb(255,255,255)"><font color="#3d85c6">Brandie Jones </font></b><div><div><div><font color="#3d85c6"><b><i>Executive </i></b></font><b style="color:rgb(61,133,198)"><i>Administrative Assistant</i></b></div></div><div><b style="color:rgb(61,133,198)"><i>Outreach Administrator </i></b></div><div><span style="background-color:rgb(255,255,255)"><font color="#3d85c6">Toyota Technological Institute</font></span></div><div><span style="background-color:rgb(255,255,255)"><font color="#3d85c6">6045 S. Kenwood Avenue</font></span></div><div><span style="background-color:rgb(255,255,255)"><font color="#3d85c6">Chicago, IL  60637</font></span></div></div><div><span style="background-color:rgb(255,255,255)"><font color="#3d85c6"><a href="http://www.ttic.edu" target="_blank">www.ttic.edu</a> </font></span></div><div><span style="background-color:rgb(255,255,255)"><font color="#3d85c6"><br></font></span></div></div></div></div></div>