"Well-posed problem" . . "inverse problem" . . "well-posed problem" . "well-posed" . . "well posedness" . . "well posed" . . "ill-posed problems" . "\\\"ill-posed\\\" problems" . "non-well-posed problems" . "ill-posed problem" . "ill-posed" . "ill posed" . . "closure" . "Well-posedness" . "well-posedness" . "Well-posed problem" . "well-posed system" . .