62 K.D. Pham
Fig. 3.3 The initial cost
problem (top) vs. the terminal
cost problem (bottom)
measure statistics are therefore, referred as “information” statistics which are ex-
tremely valuable for shaping the local performance distribution.
3.4 Problem Statements
Suffice it to say here that all the performance-measure statistics (3.31) depend in part
on the known initial condition x
i
(t
0
). Although different states x
i
(t) will result in
different values for “performance-to-come”, the values of (3.31) are, however, func-
tions of time-backward evolutions of the cumulant-generating variables H
i
00
(s, r),
˘
D
i
0
(s, r) and D
i
(s, r) that totally ignore all the intermediate values of x
i
(t) except at
the a priori initial system state x
i
(t
0
). This fact therefore makes this new optimiza-
tion problem in statistical control particularly unique as compared with the more
traditional dynamic programming class of investigations. In other words, the time-
backward trajectories (3.32)–(3.57) should be considered as the “new” dynamical
equations for which the resulting Mayer optimization and associated value function
in the framework of dynamic programming [4] thus depend on these “new” state
variables H
i
00
(s, r),
˘
D
i
0
(s, r) and D
i
(s, r). See Fig. 3.3 for further illustrations of
the initial cost problem in statistical control as opposed to the terminal cost problem
in classical control.
For notational simplicity, it is now convenient to denote the right members of the
cumulant-generating equations (3.32)–(3.57) as the mappings on the finite horizon
[t
0
,t
f
] with the rules of action
F
i,1
00
s,Y
i
00
;K
i
,K
zi
=−
A
i
(s) +B
i
(s)K
i
(s) +C
i
(s)K
zi
(s)
T
Y
i,1
00
(s)
−Y
i,1
00
(s)
A
i
(s) +B
i
(s)K
i
(s) +C
i
(s)K
zi
(s)
−K
T
i
(s)R
i
(s)K
i
(s) −Q
i
(s) −K
T
zi
(s)R
zi
(s)K
zi
(s)
F
i,1
01
s,Y
i
00
,Y
i
01
;K
i
,K
zi
=−
A
i
(s) +B
i
(s)K
i
(s) +C
i
(s)K
zi
(s)
T
Y
i,1
01
(s)
−Y
i,1
00
(s)
L
i
(s)H
i
(s)
−Y
i,1
01
(s)
A
i
(s) −L
i
(s)H
i
(s)
−Q
i
(s)
F
i,1
02
s,Y
i
02
;K
i
,K
zi
=−Y
i,1
02
(s)A
zi
(s) −
A
i
(s) +B
i
(s)K
i
(s) +C
i
(s)K
zi
(s)
T
Y
i,1
02
(s)