On-shell Lagrangians as total derivatives and the generalized Komar charge

A bstract Lagrangians which transform homogeneously under a global transformation of the fields (a global rescaling, for instance) can be written on-shell as a total derivative which has a universal, solution-independent expression, using a functional version of the Euler theorem for homogeneous functions. We study the uniqueness of this expression and how this result can be used in the construction of generalized Komar charges.