BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Date iCal//NONSGML kigkonsult.se iCalcreator 2.20.2//
METHOD:PUBLISH
X-WR-CALNAME;VALUE=TEXT:Ical
BEGIN:VTIMEZONE
TZID:Asia/Jerusalem
BEGIN:STANDARD
DTSTART:20171029T020000
TZOFFSETFROM:+0300
TZOFFSETTO:+0200
TZNAME:IST
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20170324T020000
TZOFFSETFROM:+0200
TZOFFSETTO:+0300
TZNAME:IDT
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
UID:calendar.50411.field_date.0@mathematics.huji.ac.il
DTSTAMP:20200228T122037Z
CREATED:20180109T060001Z
DESCRIPTION:Date: \n\n2:30pm to 3:30pm\n\n\n\n\nSee also: Events & Semina
rs\, ColloquiumLocation: \n\nManchester Building (Hall 2)\, Hebrew Univers
ity Jerusalem\n\n\nG.D.Birkhoff introduced a mathematical billiard inside
of a convex domain as the motion \nof a massless particle with elastic ref
lection at the boundary. A theorem of Poncelet says \nthat the billiard in
side an ellipse is integrable\, in the sense that the neighborhood of the
\nboundary is foliated by smooth closed curves and each billiard orbit nea
r the boundary \nis tangent to one and only one such curve (in this partic
ular case\, a confocal ellipse). \nA famous conjecture by Birkhoff claims
that ellipses are the only domains with this \nproperty. We show a local v
ersion of this conjecture - namely\, that a small perturbation \nof an ell
ipse has this property only if it is itself an ellipse. It turns out that
the method \nof proof gives an insight into deformational spectral rigidit
y of planar axis symmetric \ndomains and gives a partial answer to a quest
ion of P. Sarnak.\nThis is based on several papers with Avila\, De Simoi\,
G.Huang\, Sorrentino\, Q. Wei.\nThe talk will be accessible to a general
audience. \n\n Export\n \n\n \nsubscribe iCal
DTSTART;TZID=Asia/Jerusalem:20170608T143000
DTEND;TZID=Asia/Jerusalem:20170608T153000
LAST-MODIFIED:20191104T000009Z
SUMMARY:Colloquium: Vadim Kaloshin (Maryland) - 'Birkhoff Conjecture for c
onvex planar billiards and deformational spectral rigidity of planar domai
ns'
URL;TYPE=URI:https://mathematics.huji.ac.il/event/colloquium-%C2%A0vadim-ka
loshin-maryland-birkhoff-conjecture-convex-planar-billiards-and
END:VEVENT
END:VCALENDAR