  In Mechanics, the theory of standard materials is a well-known application of
Convex Analysis. However, the so-called non-associated constitutive laws cannot
be cast in the mould of the standard materials.
  From the mathematical viewpoint, a non associated constitutive law is a
multivalued operator which is not supposed to be monotone.
  A possible way to study non-associated constitutive laws by using
  Convex Analysis, proposed first in [12], consists in constructing a
"bipotential" function of two variables, which physically represents the
dissipation.
  This is a second paper on the mathematics of the bipotentials, following
math.FA/0608424 . We prove here another reconstruction theorem for a
bipotential from a convex lagrangian cover, this time using a convexity notion
related to a minimax theorem of Fan.
