Constraint analysis for variational discrete systems

Understand

A canonical formalism and constraint analysis for discrete systems subject to a variational action principle are devised.

• The formalism is equivalent to the covariant formulation, encompasses global and local discrete time evolution moves and naturally incorporates both constant and evolving phase spaces, the latter of which is necessary for a time varying discretization.
• The different roles of constraints in the discrete and the conditions under which they are first or second class and/or symmetry generators are clarified.
• The (non-) preservation of constraints and the symplectic structure is discussed; on evolving phase spaces the number of constraints at a fixed time step depends on the initial and final time step of evolution.