abstract: Lyapunov functions are important distinguishers in the theory of dynamical systems as they dissect the underlying space into an “simple” part, i.e. where the dynamics act "gradient like”, and the “interesting” part, i.e. where recurrence appears. The talk will explain a method to construct smooth and complete Lyapunov functions for vector fields (or multi functions). The method is inspired by the closely related problem of time functions in general relativity. If time permits I will give an outlook on generalizations to Lyapunov $1$-forms.