30 Nonlinear Optimal Control Theory
If we set
F
i
(t, x, y, x
′
, y
′
) = x
′
i
− f
i
(t, x, y
′
) i = 1, . . . , n, (2.6.4)
then the c ontrol problem can be written as the following proble m of Bo lza
in (n + m + 1 )- dimens ional (t, x, y)-space. The class of admissible arcs is the
set of absolutely c ontinuous functions
b
φ = (φ, η) = (φ
1
, . . . , φ
n
, η
1
, . . . , η
m
)
defined on intervals [t
0
, t
1
] such that:
(i) (t, φ(t), η
′
(t)) is in the do main of definition of the function
e
f = (f
0
, f);
(ii) (t
0
, φ(t
0
), t
1
, φ(t
1
)) is in B and η(t
0
) = 0;
(iii) the function t → f
0
(t, φ(t), η
′
(t)) is integrable; and
(iv)
F (t,
b
φ(t),
b
φ
′
(t)) = φ
′
(t) − f(t, φ(t), η
′
(t)) = 0 (2.6.5)
a.e. on [t
0
, t
1
]. The problem is to minimize the functional
g(t
0
, φ(t
0
), t
1
, φ(t
1
)) +
Z
t
1
t
0
f
0
(t, φ(t), η
′
(