Correction: SISSA algebraic geometry online seminars - Matteo GALLET

[Alessandro Nobile]

The seminar of Matteo GALLET will be held tomorrow 29 OCTOBER, not as
erroneously stated before on 29 November. 

Sorry for the spam. 
Best, 
Alessandro 

===================================================== 

Dear all,
    this is to announce the first seminar of the group of algebraic
geometry in SISSA. 

SPEAKER:    Matteo GALLET - SISSA  and  

TITLE:      Zero-sum cycles in flexible polyhedra 

WHEN:       Thursday, November 29 at 5.00pm (Rome) 

WHERE:      Link Zoom:
https://sissa-it.zoom.us/j/82882483158?pwd=bUsyY0ZwRW8vbHVhSmVEeVJWQVlzZz09
            ID riunione: 828 8248 3158
            Passcode: 446989

ABSTRACT:   We show that if a polyhedron in the three-dimensional affine
space with triangular faces is flexible, i.e., can be continuously
deformed preserving the shape of its faces, then there is a cycle of
edges whose lengths sum up to zero once suitably weighted by 1 and -1.
We do this via elementary combinatorial considerations, made possible by
a well-known compactification of the three-dimensional affine space as a
quadric in the four-dimensional projective space. The compactification
is related to the Euclidean metric, and allows us to use a simple
degeneration technique that reduces the problem to its one-dimensional
analogue, which is trivial to solve. This is a joint work with G.
Grasegger, J. Legerský, and J. Schicho. 

Best regards,
Alessandro