ABSTRACT
The above discussion obviously applies also when
0(x) and φ(χ) are classical variables instead of quantum
mechanical operators.
The replacement of δ-functions by a smooth func-
tion P [σ , φ ] such as the Gaussian (A. 6) smears up the
variable φ its e l f in contrast to smearing its spatial
dependence as in (A. 3) . It rem oves some unpleasant
mathematical features of δ-functions. It also produces
extra terms like the 1/w in (A. 16) which must be care-
produce different extra terms.