<div dir="ltr"><div class="m_-8685053970642002846gmail-m_-4291882943031079788gmail-ajy">[Apologies for multiple copies]<br></div><br>Dear all,<br><br>Let me advertise our next ERATO MMSD project 
<span class="m_-8685053970642002846gmail-m_-4291882943031079788gmail-m_6832220814482882016gmail-m_547872329642204051m_1674442457263079573gmail-il"><span class="m_-8685053970642002846gmail-m_-4291882943031079788gmail-m_6832220814482882016gmail-il"><span class="m_-8685053970642002846gmail-m_-4291882943031079788gmail-il"><span class="m_-8685053970642002846gmail-il">colloquium</span></span></span></span> talk by Ichiro Hasuo on 25th April, 16:00-. Please find the 
title and the abstract below. You are all invited.<br><br>Sincerely,<br>--<br>Natsuki Urabe<br><a href="mailto:urabenatsuki@is.s.u-tokyo.ac.jp" target="_blank">urabenatsuki@is.s.u-tokyo.ac.j<wbr>p</a><br>The University of Tokyo, ERATO MMSD<br><br>-----<br><span style="font-size:14pt;font-family:Arial;color:rgb(0,0,0);background-color:rgb(255,255,255);font-weight:700;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Wed 25 April 2018, 16:00–17:00</span><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:8pt;font-family:Arial;color:rgb(255,0,0);background-color:rgb(255,255,255);font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">ERATO MMSD Takebashi Site Common Room 3</span><span style="font-size:8pt;font-family:Arial;color:rgb(0,0,0);background-color:rgb(255,255,255);font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="m_-8685053970642002846gmail-kix-line-break"></span><a href="http://group-mmm.org/eratommsd/access.html" style="text-decoration:none" target="_blank"><span style="font-size:8pt;font-family:Arial;color:rgb(17,85,204);background-color:rgb(255,255,255);font-weight:400;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">http://group-mmm.org/<wbr>eratommsd/access.html</span></a></p><br><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:rgb(255,255,255);font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Ichiro Hasuo (</span><a href="http://www.nii.ac.jp/" style="text-decoration:none" target="_blank"><span style="font-size:11pt;font-family:Arial;color:rgb(17,85,204);background-color:rgb(255,255,255);font-weight:400;font-style:normal;font-variant:normal;text-decoration:underline;vertical-align:baseline;white-space:pre-wrap">National Institute of Informatics</span></a><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:rgb(255,255,255);font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">), </span><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:rgb(255,255,255);font-weight:700;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"> </span><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:rgb(255,255,255);font-weight:700;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><br class="m_-8685053970642002846gmail-kix-line-break"></span><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:rgb(255,255,255);font-weight:700;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Approximating Reachability Probabilities by (Super-)Martingales</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:9pt;font-family:Arial;color:rgb(102,102,102);background-color:rgb(255,255,255);font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">Reachability is a fundamental problem in the analysis of probabilistic systems. It is well-known that reachability probabilities are efficiently computed for finite-state systems by linear programming. However, this LP method does not apply to systems that have infinitely many configurations, such as probabilistic programs and parametric systems. In such a case, we have to rely on a parametric witness (i.e. a function) for over- or under-approximating reachability probabilities. A well-studied class of such witnesses is that of supermartingales. In this talk I will talk about our recent results that refine existing supermartingale-based methods. The technical keys to those results are: choice of a suitable martingale concentration lemma for over-approximation; and a categorical axiomatization of supermartingales by coalgebras and corecursive algebras. The talk is based on my joint work with Natsuki Urabe, Masaki Hara, Bart Jacobs, Toru Takisaka and Yuichiro Oyabu.</span></p><br></div>