Giving a sequence $$P=(P_{n})_{n}$$
P
=
(
P
n
)
n
of kernels on a measurable space (or just a semigroup $$(P_{t})_{t\in (0,\infty )}$$
(
P
t
)
t
∈
(
0
,
∞
)
), we are interested to describe the “semi-excessive” functions w.r. to P, i.e., measurable functions f, such that $$\lim \nolimits _{n\rightarrow \infty } P_{n}(f)=f$$
lim
n
→
∞
P
n
(
f
)
=
f
(or $$\lim \nolimits _{t\rightarrow 0} P_{t}(f)=f$$
lim
t
→
0
P
t
(
f
)
=
f
). We extend in this frame the famous Korovkin result on the uniform convergence of $$P_{n}(f)$$
P
n
(
f
)
to f on a class of measurable functions f, but beside that, we give a pointwise convergence result which may be a useful tool in Probabilistic Potential Theory as well Right Processes.