Michel GRANGER – Logarithmic differential forms and and vector fields : geometric and differential aspects.

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19 novembre 2015    
In this talk I will first recall Kyoji Saito’s theory of logarithmic differential forms and vector fields, paying a particular attention to the freeness condition, and explain related problem, notably the logarithmic comparison question. I will also develop the notion of logarithmic residues along a divisor. I will review a number of results by David Mond and/or Mathias Schulze and myself, including a property of symmetry of the b-function and a characterisation of divisors with normal crossings in codimension one. This characterization answers a question of K. Saito. I will, according to the time left, briefly explain explain recent developments by Delphine Pol, which concern the set of valuations of residues along reduced plane curves. http://perso.math.univ-angers.fr/spip.php?rubrique11 Michel GRANGER [