  A non-perturbative approach based on the Fock decomposition of the state
vector and its truncation is discussed. In order the non-perturbative
renormalization procedure after truncation could eliminate infinities, it
should be the sector dependent. We clarify the meaning of this procedure in a
toy model. Then we demonstrate stability, relative to the increasing cutoff, of
the anomalous magnetic moment found using the sector dependent renormalization
scheme in Yukawa model.
