Necessary and sufficient conditions in terms of Lebesgue sets are presented for the following two insertion properties for real-valued functions defined on a topological space: (1)
g
⩽
f
g \leqslant f
there is a continuous function
h
h
such that
g
⩽
h
⩽
f
g \leqslant h \leqslant f
, and for each
x
x
for which
g
(
x
)
>
f
(
x
)
g(x) > f(x)
then
g
(
x
)
>
h
(
x
)
>
f
(
x
)
g(x) > h(x) > f(x)
. (2)
g
>
f
g > f
there is a continuous function
h
h
such that
g
>
h
>
f
g > h > f
.