Erceg, MarcoMichelangeli, Alessandro2017-10-102017-10-102017https://openscience.sissa.it/handle/1963/35298We realise the Hamiltonians of contact interactions in quantum mechanics within the framework of abstract Friedrichs systems. In particular, we show that the construction of the self-adjoint (or even only closed) operators of contact interaction supported at a fixed point can be associated with the construction of the bijective realisations of a suitable pair of abstract Friedrich operators. In this respect, the Hamiltonians of contact interaction provide novel examples of abstract Friedrich systems.enAbstract Friedrichs systemsGrubb extension theoryPreprint48/2017/MATE