Diagrammatic representation and inference 12th International Conference, Diagrams 2021, Virtual, September 28–30, 2021 : proceedings - Basu, Amrita 1953-; Stapleton, Gem; Linker, Sven 1983-; Legg, Catherine; Manalo, Emmanuel; Viana, Petrucio (Lecture notes in computer science, 2021)