“…This divergence is not a true metric (for example, because it does not satisfy the triangle inequality), but it still enjoys various properties which make it a useful substitute for a distance (for example, B(x, y) ≥ 0 for all x ∈ dom(b) and y ∈ Int(dom(b)) and B(x, y) = 0 if and only if x = y ∈ U : see, for instance, [40, Proposition 4.13(III)]). Many more details about this notion, including historical details, a long list of relevant references, various mathematical properties, and a thorough re-examination, can be found in the recent paper [40]. (ii) A semi-Bregman function generalizes the notion of "a Bregman function" (the term "semi-Bregman function" seems to be new, although it has been used here and there without this explicit name Here we briefly recall very well-known versions of the proximal gradient method (the proximal point algorithm).…”