Résumé
This special issue of Algorithmica to the 13th International Symposium on Parameterized and Exact Computation (IPEC) held in Helsinki, Finland. IPEC (formerly IWPEC) is a series of international symposia covering research in all aspects of parameterized and exact algorithms and complexity. Started in 2004 as a biennial workshop, it became an annual event in 2009 and is now a highly recognized annual meeting. This special issue is a successor of following special issue volumes of Algorithmica: volumes 64(1)-2012 and 65(4)-2013 dedicated to IPEC 2010, held in Chennai (India); volume 71(3)-2015 dedicated to IPEC 2013, held in Sophia Antipolis (France); volume 75(2)-2016 dedicated to IPEC 2014, held in Wrocław (Poland); volume 79(1)-2017 dedicated to IPEC 2015, held in Patras (Greece); volume 81(2)-2019 dedicated to IPEC 2016, held in Aarhus (Denmark); volume 81(10)-2019 dedicated to IPEC 2017, held in Vienna (Austria).