We consider the fractional powers of singular (point-like) perturbations of
the Laplacian, and the singular perturbations of fractional powers of the
Laplacian, and we compare such two constructions focusing on their perturbative
structure for resolvents and on the local singularity structure of their
domains. In application to the linear and non-linear Schr\"{o}dinger equations
for the corresponding operators we outline a programme of relevant questions
that deserve being investigated.Comment: Published on J. Math. Phys. (2018