Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:These assumptions are related to a weaker form of the second-order sufficient conditions [16, 6], which does not imply the existence of a locally convex augmented Lagrangian as is the case in [5, 9, 15, 14, 26, 30, 31].
Category: