Abstract
The paper generalises the notion of landmarks
for reasoning about planning problems involving
propositional and numeric variables. Intuitively,
numeric landmarks are regions in the metric space
defined by the problem whose crossing is necessary
for its resolution. The paper proposes a relaxationbased method for their automated extraction directly from the problem structure, and shows how
to exploit them to infer what we call disjunctive and
additive hybrid action landmarks. The justification
of such a disjunctive representation results from
the intertwined propositional and numeric structure
of the problem. The paper exercises their use in
two novel admissible LP-Based numeric heuristics,
and reports experiments on cost-optimal numeric
planning problems. Results show the heuristics are
more informed and effective than previous work for
problems involving a higher number of (sub)goals