“…One of the powerful ideas behind previous and current approaches is to devise heuristics from a computationally effective relaxation or abstraction of the targeted problem. In particular, the solution of the relaxed problem can be used as a means to estimate the actual distance or cost to the problem goal Pioneered by Hoffman ( 2003), the interval-based relaxation (Aldinger et al, 2015;Gregory, Long, Fox, & Beck, 2012) has been the principle most used to extract such a heuristic information in the numeric extension to classical planning. These heuristics come in different flavours, including as metric extensions of the relaxed planning graph (Koehler, 1998;Hoffmann, 2003;Gerevini, Saetti, & Serina, 2008;Coles et al, 2012Coles et al, , 2013.…”