“…There is a lot of prior work related to the method proposed in this paper. The work on variable metric bundle methods [9,18,25,36,37,[40][41][42]45,49,50,54,61,63,66,70] and (inexact) proximal Newton-type methods [8,11,12,27,38,39,43,44,51,59,60,62,71] are probably the most closely related, though our method differs in key ways arising from our assumed access methods. Proximal Newton methods are similar in philosophy to our approach, as both types of methods really shine when the structured part of the objective can be minimized efficiently.…”