Vanishing cycles and mutation

This is the writeup of a talk given at the European Congress of Mathematics, Barcelona. It considers Picard-Lefschetz theory from the Floer cohomology viewpoint.Comment: 20 pages, LaTeX2e. TeXnical problem should now be fixed, so that the images will appear even if you download the .ps fil

The Theory of Music and the harmony of the Universe at the 16th century

Colloquium « Sing Aloud harmonious spheres : Music, philosophy and the order of the universe in the Renaissance », University of Warwick, Venice, 12-15 may 2011