The current paper initially studies the optimal control of linear
ψ-Hilfer fractional derivatives with state-dependent control constraints
and optimal control for a particular type of cost functional. Then, we
investigate the approximate controllability of the abstract fractional
semilinear differential inclusion involving ψ-Hilfer fractional derivative
in reflexive Banach spaces. It is known that the existence, uniqueness, optimal
control, and approximate controllability of fractional differential equations
or inclusions have been demonstrated for a similar type of fractional
differential equations or inclusions with different fractional order derivative
operators. Hence it has to research fractional differential equations with more
general fractional operators which incorporate all the specific fractional
derivative operators. This motivates us to consider the ψ-Hilfer
fractional differential inclusion. We assume the compactness of the
corresponding semigroup and the approximate controllability of the associated
linear control system and define the control with the help of duality mapping.
We observe that convexity is essential in determining the controllability
property of semilinear differential inclusion. In the case of Hilbert spaces,
there is no issue of convexity as the duality map becomes simply the identity
map. In contrast to Hilbert spaces, if we consider reflexive Banach spaces,
there is an issue of convexity due to the nonlinear nature of duality mapping.
The novelty of this paper is that we overcome this convexity issue and
establish our main result. Finally, we test our outcomes through an example.Comment: 39 page