Graph-Based Representations in Pattern Recognition 12th IAPR-TC-15 International Workshop, GbRPR 2019, Tours, France, June 19-21, 2019, Proceedings - Conte, Donatello; Conte, Donatello; Ramel, Jean-Yves; Ramel, Jean-Yves; Foggia, Pasquale; Foggia, Pasquale (Springer International Publishing : Imprint: Springer, 2019)