“…In this paper we utilise novel methods of Calculus of Variations in L ∞ in order to lay the rigorous mathematical foundations of the FOT problem. Motivated by developments underpinning the papers [38,40,41,42], we pose FOT as a minimisation problem in L ∞ with PDE constraints as well as unilateral constraints, studying the direct as well as the inverse FOT problem, both in L p for finite p and in L ∞ . Further, we derive the relevant variational inequalities in L p for finite p and in L ∞ that the constrained minimisers satisfy, which involve (generalised) Lagrange multipliers.…”