e previously introduced the change of measure in the section
( Change of measure definition
) with the defining
property
(change of measure requirement)
where the
is any process,
is some martingale process starting at
,
is the original expectation and
is the new expectation defined by the process
.
In context of the present
chapter
where we restricted our attention to Markov processes
.
We are seeking a transformation rule for a new propagator
that corresponds to
:
for any Markov processes
.
Let
be a markov process
.
According to the formula ( change of
measure requirement)
If we set
for a variety of
then
Consequently,
Summary
The change of measure given by the Markov process
according to the
formula
transforms the pair
into the pair
according to the
formulas