Formal Grammar 20th and 21st International Conferences, FG 2015, Barcelona, Spain, August 2015, Revised Selected Papers. FG 2016, Bozen, Italy, August 2016, Proceedings - Foret, Annie; Morrill, Glyn; Muskens, Reinhard; Osswald, Rainer; Pogodalla, Sylvain (Springer Berlin Heidelberg : Imprint: Springer, 2016)