Première valeur propre du laplacien, volume conforme et chirurgies

We define a new differential invariant a compact manifold by , where V c ( M , [ g ]) is the conformal volume of M for the conformal class [ g ], and prove that it is uniformly bounded above. The main motivation is that this bound provides a upper bound of the Friedlander-Nadirashvili invariant defined by . The proof relies on the study of the behaviour of when one performs surgeries on M .