Stability and robustness for saddle-point dynamics through monotone mappings

Motivated by recent interest in saddle-point dynamics, where, given a convex in x and concave in y function, trajectories follow the steepest descent in x and the steepest ascent in y, and where convergence of trajectories to saddle points is desired, this note revisits the maximal monotone mapping approach to saddle-point dynamics, mildly improves one convergence result, and proposes new results on the robustness of pointwise asymptotic stability of the set of saddle points. The results apply to nonsmooth convex/concave functions and constraints, and - as a special case - to projected saddle-point dynamics.