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SUMMARY:Non-Negative Polynomials versus Sums of Squares
DTSTART:20131023T151500
DTEND:20131023T160000
DTSTAMP:20260528T020303Z
UID:62372c677eaa64b4ba132e028c060b54b60f55a7c117bf78f2e9c451
CATEGORIES:Conferences - Seminars
DESCRIPTION:Bernd Sturmfels (UC Berleley and MPI Bonn)\nAbstract: We discu
 ss the geometry underlying the difference between non-negative \npolynomi
 als and sums of squares. The hypersurfaces that discriminate these \ntwo 
 cones for ternary sextics and quaternary quartics are shown to be \nNoeth
 er-Lefschetz loci of K3 surfaces. The projective duals of these\nhypersurf
 aces are defined by rank constraints on Hankel matrices. We \ncompute the
 ir degrees using numerical algebraic geometry\, thereby verifying \nresul
 ts due to Maulik and Pandharipande. The non-SOS extreme rays of the two \
 ncones of non-negative forms are parametrized respectively by the Severi 
 \nvariety of plane rational sextics and by the variety of quartic symmetro
 ids.
LOCATION:MEB331 http://plan.epfl.ch/?lang=fr&room=ME+B331
STATUS:CONFIRMED
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