Title: Variational structure recognition for nonholonomic mechanics

Abstract: Classical holonomic mechanical systems, and discrete analogues
of those, and also classical field theories, admit well known
variational formulations. Solutions of these systems are critical
points of an action functional subject to a fixed-boundary condition.

But classical holonomic mechanical systems also have a well known
symplectic formulation. This can be derived from the
corresponding variational principle using a simple
procedure, which only refers to generic concepts, such as "solution",
and "boundary". The same procedure can be applied in a variety of
contexts as a way or recognizing or identifying analogues of
symplectic structures. This idea is useful and compelling in
discrete analogues of these systems, and can be used to derive
symplectic integration algorithms.

So what happens when the procedure is applied, for the purpose of
recognizing analogues of the symplectic structure, to nonholonomic
systems, which are known not to be, in general, symplectic?

Reference: Variational development of the semi-symplectic geometry of
nonholonomic mechanics. Accepted Rep. Math. Phys., 42pp.
http://math.usask.ca/~patrick/PatrickGW-2005-3.pdf