“…A rich array of results have been established on the well-posedness and closely related problems. Interested readers can consult some of the references listed here, see, e.g., [1,3,4,5,6,8,9,11,12,13,14,15,16,17,22,18,19,23,24,25,27,28,29,30,31,32,33,34]. This list is by no means exhaustive.…”