LAMA 2008 and 2011 Silvia

LAMA is a propositional planning system based on heuristic search with landmarks. This paper describes two versions of LAMA that were entered into the 2011 International Planning Competition: the original LAMA as developed for the 2008 competition and a new re-implementation of LAMA that uses the latest version of the Fast Downward Planning Framework. Landmarks are propositions that must be true in every solution of a planning task. LAMA uses a heuristic derived from landmarks in conjunction with the well-known FF heuristic. LAMA builds on the Fast Downward Planning System using non-binary (but finite domain) state variables and multiheuristic search. A weighted A∗ search is used with iteratively decreasing weights, so that the planner continues to search for plans of better quality until the search is terminated. LAMA combines cost-to-goal and distance-to-goal estimates with the aim of finding good solutions using rea-