“…A solution of (HJ S ) means a lower semicontinuous function ϕ : R S + −→ IR ∪ {+∞} such that ϕ(S) = 0 and for every x ∈ R S + , for every ζ ∈ ∂ P ϕ(x) (if any), we have h(x, ζ) + 1 = 0 (we say that ϕ(x) is a proximal solution, see [8]). This is equivalent to the statement that ϕ is a lower semicontinuous viscosity solution of the following Hamilton-Jacobi equation: It is well-known that the minimal time function T (·, S) is a solution of (HJ S ) if we replace R S + by R S + \ S (see for example [1,3,7,18,22]), but it is never a solution on R S + since for all α ∈ S we have 0 ∈ ∂ P T (·, S)(α) and h(α, 0) = 0. In [11], Clarke and Nour study the Hamilton-Jacobi equation (HJ S ) in the case S = {α 0 } (we denote this equation by (HJ α0 )) 2 .…”