Frédéric Peschanski Joël-Alexis Bialkiewicz Modelling and Verifying Mobile Systems Using pi-Graphs. 437-448 2009 SOFSEM https://doi.org/10.1007/978-3-540-95891-8_40 conf/sofsem/2009 db/conf/sofsem/sofsem2009.html#PeschanskiB09