BEGIN:VCALENDAR
PRODID:-//PSU Mathematics Department//Seminar iCalendar Generator//EN
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CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:Geometry Luncheon Seminar
X-WR-TIMEZONE:America/New_York
BEGIN:VTIMEZONE
TZID:America/New_York
X-LIC-LOCATION:America/New_York
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:19700308T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:19701101T020000
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150826T120000
DTEND;TZID=America/New_York:20150826T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29000
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150902T120000
DTEND;TZID=America/New_York:20150902T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29001
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150909T120000
DTEND;TZID=America/New_York:20150909T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29002
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150916T120000
DTEND;TZID=America/New_York:20150916T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=28999
SUMMARY:Geometry Luncheon Seminar - Products of two symmetries of order two
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: Products of two symm
etries of order two\nSpeaker: Oleg Viro\, Stony Brook\nAbstract: Many grou
ps (e.g.\, the isometry groups of all classical space forms\, i.e. Euclide
an\, hyperbolic and elliptic spaces) are generated by involutions. Moreove
r\, each element can be presented as a product of two involutions. In fact
\, any group admits an embedding into a group in which any element is a pr
oduct of two involutions. The presentations of isometries in this form giv
es rise to a fast pictorial calculation of their compositions. It brings i
n a geometry into the set of involutions. One can extract a complete set o
f relations among the symmetries.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150930T120000
DTEND;TZID=America/New_York:20150930T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29005
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151007T120000
DTEND;TZID=America/New_York:20151007T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29006
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151014T120000
DTEND;TZID=America/New_York:20151014T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29007
SUMMARY:Geometry Luncheon Seminar - Skewers
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: Skewers\nSpeaker: Se
rgei Tabachnikov\, Penn State\nAbstract: The skewer of a pair of skew line
s in space is their common perpendicular. To configuration theorems of pla
ne projective geometry involving points and lines (such as Pappus or Desar
gues) there correspond configuration theorems in space: points and lines i
n the plane are replaced by lines is space\, the incidence between a line
and a point translates as the intersection of two lines at right angle\, a
nd the operations of connecting two points by a line or by intersecting tw
o lines at a point translate as taking the skewer of two lines. These conf
iguration theorems hold in elliptic\, Euclidean\, and hyperbolic geometrie
s. This correspondence principle extends to plane configuration theorems
involving polarity. For example\, the theorem that the three altitudes of
a triangle are concurrent corresponds to the Petersen-Morley theorem that
the common normals of the opposite sides of a space right-angled hexagon h
ave a common normal. \nI shall discuss two approaches to the proof\,an ell
iptic and a hyperbolic one. I shall also discuss the skewer versions of t
he Sylvester problem: given a finite collection of pairwise skew lines suc
h that the skewer of any pair intersects at least one other line at right
angle\, do all the line have to share a skewer? The answer is positive in
the elliptic and Euclidean geometries\, but negative in the hyperbolic one
.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151021T120000
DTEND;TZID=America/New_York:20151021T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29008
SUMMARY:Geometry Luncheon Seminar - Length spectrum for real convex project
ive structures on manifolds
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: Length spectrum for
real convex projective structures on manifolds\nSpeaker: Thomas BarthelmÃ©
\, Penn State\nAbstract: A convex projective manifold is a manifold obtain
ed as a quotient $M = \\Omega/\\Gamma$\, where $\\Omega$ is a convex set i
n the real projective $n$-space and $\\Gamma$ is a discrete subgroup of $
PGL(n+1\, \\mathbb{R})$. Convex projective manifolds come naturally equip
ped with a Finsler metric\, called the Hilbert metric. The most classical
example is to take $\\Omega$ to be the ball in the projective space\, and
then the metric truns out to be Riemannian hyperbolic\, but many non-Riem
annian examples exists. In this talk\, I will review convex projective str
uctures on compact manifolds\, talk about what is already known about its
marked length spectrum\, and present new results about the unmarked length
spectrum. This is part of a work in progress with L. Marquis and A. Zimme
r.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151028T120000
DTEND;TZID=America/New_York:20151028T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29009
SUMMARY:Geometry Luncheon Seminar - Edge flipping for fun (and profit?)
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: Edge flipping for fu
n (and profit?)\nSpeaker: Ken Stephenson\, University of Tennessee\nAbstra
ct: Our interest is in triangulation graphs. Using circle packings\nyou ca
n impose geometry on these purely combinatoric structures. What\nhappens t
o that geometry when you "flip" an edge in the graph? Nature\nseems to kno
w how to handle this. We will play around with some examples\ninvolving bu
ckyballs and graphene carbon structures and see how well we\ncan do.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151104T120000
DTEND;TZID=America/New_York:20151104T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29010
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151111T120000
DTEND;TZID=America/New_York:20151111T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29011
SUMMARY:Geometry Luncheon Seminar - On invertibility of adjacency matrices
of random $d$-regular digraphs.
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: On invertibility of
adjacency matrices of random $d$-regular digraphs.\nSpeaker: Anna Lytova\,
University of Alberta\, CA\nAbstract: We consider d-regular directed grap
hs on n vertices. Every vertex of such graphs has exactly d in-neighbors a
nd d out-neighbors. We show that under some minor restrictions on d\, the
probability that an adjacency matrix of a random d-regular digraph is sing
ular tends to zero with d growing to infinity. To this end\, we establish
a few expansion properties of d-regular digraphs\, in particular\, a Littl
ewood--Offord type anti-concentration property. This is a joint work with
A. Litvak\, K. Tikhomirov\, N. Tomczak-Jaegermann\, and P. Youssef.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151118T120000
DTEND;TZID=America/New_York:20151118T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29012
SUMMARY:Geometry Luncheon Seminar - Sharp Trace-Sobolev inequalities of ord
er 4
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: Sharp Trace-Sobolev
inequalities of order 4\nSpeaker: Antonio Ache\, Princeton University\nAbs
tract: We establish sharp Sobolev inequalities of order four on Euclidean
d-balls for d greater than or equal to four. When d=4\, our inequality gen
eralizes the classical second order Lebedev-Milin inequality on Euclidean
2-balls. Our method relies on the use of scattering theory on hyperbolic d
-balls. As an application\, we characterize the extremals the main term in
the log-determinant formula corresponding to the conformal Laplaciancoupl
ed with the boundary Robin operator on Euclidean 4-balls.This is joint wor
k with Alice Chang.
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151125T120000
DTEND;TZID=America/New_York:20151125T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29013
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151202T120000
DTEND;TZID=America/New_York:20151202T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29014
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA\nSpeaker: Carina
Curto\, Penn State
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151209T120000
DTEND;TZID=America/New_York:20151209T133000
LOCATION:MB114
URL:http://www.math.psu.edu/seminars/meeting.php?id=29015
SUMMARY:Geometry Luncheon Seminar - TBA
DESCRIPTION:Seminar: Geometry Luncheon Seminar\nTitle: TBA\nSpeaker: Jeffre
y Case\, Penn State
END:VEVENT
END:VCALENDAR