<div dir="ltr"><p class="gmail-MsoTitle" style="margin:0cm 0cm 0.0001pt;text-align:center;font-size:24pt;font-family:"New York",serif;font-weight:bold;text-decoration-line:underline"><span style="font-size:18pt;font-family:"Times New Roman",serif">SEMINARIO
DI MATEMATICA</span></p>

<p class="gmail-MsoTitle" style="margin:0cm 0cm 0.0001pt;text-align:center;font-size:24pt;font-family:"New York",serif;font-weight:bold;text-decoration-line:underline"><span style="font-size:10pt;font-family:"Times New Roman",serif"><span style="text-decoration-line:none"> </span></span></p>

<p class="MsoNormal" align="center" style="margin:0cm 0cm 0.0001pt 9pt;text-align:center;line-height:18pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><span style="font-size:16pt;font-family:"Times New Roman",serif">Martedì 25 giugno 2019</span></b><b><span style="font-size:16pt;font-family:"Times New Roman",serif"></span></b></p>

<p class="MsoNormal" align="center" style="margin:0cm 0cm 0.0001pt 9pt;text-align:center;line-height:18pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif">ore 11:00</span></p>

<p class="MsoNormal" align="center" style="margin:0cm 0cm 0.0001pt 9pt;text-align:center;line-height:18pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif"> </span></p>

<p class="MsoNormal" align="center" style="margin:0cm 0cm 0.0001pt 9pt;text-align:center;line-height:18pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><u><span style="font-size:16pt;font-family:"Times New Roman",serif">Scuola Normale Superiore</span></u></p>

<p class="MsoNormal" align="center" style="margin:0cm 0cm 0.0001pt 9pt;text-align:center;line-height:18pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif">Pisa</span></p>

<p class="MsoNormal" align="center" style="margin:0cm 0cm 0.0001pt 9pt;text-align:center;line-height:18pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span lang="EN-US" style="font-size:16pt;font-family:"Times New Roman",serif">Aula Mancini</span></p>

<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><u><span lang="EN-US" style="font-size:10pt;font-family:"Times New Roman",serif"><span style="text-decoration-line:none"> </span></span></u></b></p>

<p class="MsoNormal" align="center" style="text-align:center;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><span lang="EN-US" style="font-size:20pt;font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">Michael Overton</span></b><b><span lang="EN-US" style="font-size:20pt;font-family:"Times New Roman",serif"></span></b></p>

<h4 align="center" style="margin:0cm 0cm 0.0001pt;text-align:center;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;break-after:avoid;font-size:12pt;font-family:Cambria,serif;color:rgb(79,129,189);font-style:italic"><span lang="EN-US" style="font-family:"Times New Roman",serif;color:windowtext;font-weight:normal;font-style:normal">(</span><span lang="EN-US" style="font-family:"Times New Roman",serif;color:rgb(34,34,34);background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-weight:normal;font-style:normal">New York University</span><span lang="EN-US" style="font-family:"Times New Roman",serif;color:windowtext;font-weight:normal;font-style:normal">)</span></h4>

<p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><i><span lang="EN-US" style="font-family:"Times New Roman",serif"> </span></i></p>

<p class="MsoNormal" align="center" style="text-align:center;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif">Terrà un
seminario dal titolo:</span></p>

<p class="MsoNormal" align="center" style="text-align:center;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><span style="font-size:10pt;font-family:"Times New Roman",serif"> </span></b></p>

<p class="MsoNormal" align="center" style="text-align:center;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><span lang="EN-US" style="font-size:22pt;font-family:"Times New Roman",serif">“</span></b><b><span style="font-size:22pt;font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">Crouzeix’s conjecture</span></b><b><span lang="EN-US" style="font-size:22pt;font-family:"Times New Roman",serif">”</span></b></p>

<p class="MsoNormal" align="center" style="text-align:center;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><i><span lang="EN-US" style="font-size:10pt;font-family:"Times New Roman",serif"> </span></i></b></p>

<p class="MsoNormal" align="center" style="text-align:center;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><i><span lang="EN-US" style="font-size:10pt;font-family:"Times New Roman",serif"> </span></i></b></p>

<p class="MsoNormal" style="text-align:justify;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><b><i><span lang="EN-US" style="font-family:"Times New Roman",serif">Abstract:</span></i></b></p>

<p class="MsoNormal" style="text-align:justify;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span lang="EN-US" style="font-family:"Times New Roman",serif">Crouzeix's conjecture is among the most intriguing
developments in matrix theory in recent years. Made in 2004 by Michel Crouzeix,
it postulates that, for any polynomial p and any matrix A, ||p(A)|| <= 2
max(|p(z)|: z in W(A)), where the norm is the 2-norm and W(A) is the field of
values (numerical range) of A, that is the set of points attained by v*Av for
some vector v of unit length.  Crouzeix proved in 2007 that the inequality
above  holds if 2 is replaced by 11.08, and recently this was greatly
improved by Palencia, replacing 2 by 1+sqrt(2).  Furthermore, it is known
that the conjecture holds in a number of special cases, including
n=2.  We use nonsmooth optimization to investigate the conjecture
numerically by locally minimizing the “Crouzeix ratio”, defined as the quotient
with numerator the right-hand side and denominator the left-hand side of the conjectured
inequality. We also present local nonsmooth variational analysis of the Crouzeix
ratio at conjectured global minimizers.  All our results strongly support
the truth of Crouzeix’s conjecture.</span></p>

<p class="MsoNormal" style="text-align:justify;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span lang="EN-US" style="font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"> </span></p>

<p class="MsoNormal" style="text-align:justify;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span lang="EN-US" style="font-size:16pt;font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"> </span></p>

<p class="MsoNormal" style="text-align:justify;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">Tutti gli
interessati sono invitati a partecipare.</span></p>

<p class="MsoNormal" style="text-align:justify;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"> </span></p>

<p class="MsoNormal" style="text-align:justify;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">Classe di
Scienze</span><b><i><span style="font-size:16pt;font-family:"Times New Roman",serif"></span></i></b></p><p class="MsoNormal" style="text-align:justify;margin:0cm 0cm 0.0001pt;font-size:12pt;font-family:TradeGothicPl-CondEighteen"><span style="font-size:16pt;font-family:"Times New Roman",serif;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><br></span></p><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>Valeria Giuliani</div><div>Scuola Normale Superiore</div><div>Servizio alla Didattica e Allievi</div><div>tel. 050 509260</div><div>Piazza dei Cavalieri, 7</div><div>56126 Pisa</div><div>E-mail: <a href="mailto:valeria.giuliani@sns.it" target="_blank">valeria.giuliani@sns.it</a></div><div>E-mail: <a href="mailto:classi@sns.it" target="_blank">classi@sns.it</a></div></div></div></div></div>

<p></p>

-- <br />
Hai ricevuto questo messaggio perché sei iscritto al gruppo "Matematici.Esterni.SNS" di Google Gruppi.<br />
Per annullare l'iscrizione a questo gruppo e non ricevere più le sue email, invia un'email a <a href="mailto:matematici.esterni.sns+unsubscribe@sns.it">matematici.esterni.sns+unsubscribe@sns.it</a>.<br />
Per visualizzare questa discussione sul Web, visita <a href="https://groups.google.com/a/sns.it/d/msgid/matematici.esterni.sns/CAGKKDBkif_muyyDryjA4dnB016AkAKJcqV03v%3DRwGaUqqZAukA%40mail.gmail.com?utm_medium=email&utm_source=footer">https://groups.google.com/a/sns.it/d/msgid/matematici.esterni.sns/CAGKKDBkif_muyyDryjA4dnB016AkAKJcqV03v%3DRwGaUqqZAukA%40mail.gmail.com</a>.<br />