Back to the HomePage.

Caveats for the options

Here, we document some aspects of the command-line syntax that may be unintuitive or complicated.

Setting the "cost type" for landmark heuristics

For mostly historical reasons, specifying the cost type (see Doc/Heuristic) for landmark heuristics (lmcount, see Doc/Heuristic#Landmark-count_heuristic) is currently complicated. Here's the complete set of rules:

There are two relevant options:

1. lm_cost_type of the landmark generation method (currently only used by lm_rhw)

2. transform of the landmark heuristic declaration (lmcount). Pass e.g. transform=adapt_costs(one) for unit costs.

The cost type of the landmark heuristic is determined by option 1. when using admissible=false and by option 2. when using admissible=true.

Note: Setting the cost type for the LAMA-FF synergy's master (see Doc/Heuristic#LAMA-FF_synergy_master) follows the same rules as the landmark heuristic. The cost type of the synergy's FF heuristic is determined by option 2.

Using "preferred operators" with landmark heuristics

Unlike all other (current) heuristics, the landmark heuristic (lmcount, see Doc/Heuristic#Landmark-count_heuristic) requires a special setting pref=true to enable preferred operator support. Hence, to use preferred operators with that heuristic, two things must be done at the moment:

1. Set pref=true in the heuristic specification.

2. Include the heuristic in the list of heuristics in the preferred specification of the search engine.