1941 (Dines [3]) |
(Dines Theorem) is convex. Moreover, if |
1961 (Brickmen [1]) |
is convex if |
1995 (Ramana & Goldman [11]) Unpublished |
is convex if and only if |
is convex if |
|
1998 (Polyak [10]) |
is convex if |
is convex if |
|
2016 (Bazán & Opazo [5]) |
is convex if and only if where |