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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 is currently complicated. Here's the complete set of rules:

If you use the LAMA-FF synergy

There are two relevant options:

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

2. transform of the synergy declaration (lm_ff_syn). Pass e.g. transform=adapt_costs(one) for unit costs.

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

The cost type of the synergy's FF heuristic is determined by option 2. It implies four different settings for admissible=false. If LAMA-FF synergy is determined to use a single cost type, set option 1. and 2. to the same cost type.

If you do not use the LAMA-FF synergy

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.

Using preferred operators with the lmcount heuristic

Unlike all other (current) heuristics, the lmcount 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.