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Option Syntax

The configuration syntax changed slightly in April 2011.

Meaning of the call syntax documentation

All parameters can be specified by keyword or by position. Once a parameter is specified by keyword, the rest of the parameters must be specified by keyword too. Some parameters have default values and are optional. These parameters are documented in the form keyword = defaultvalue.

Consider the following example:

name(p, qs, r, s=v1, t=Enum1)

• p (type_p): some explanation

• qs (list of type_q): some explanation

• r (type_r): some explanation

• s (type_s): some explanation

• t (Enum): some explanation

  • Enum0: some explanation
  • Enum1: some explanation
  • Enum2: some explanation

Parameters p, qs and r are mandatory. qs is a list parameter. List parameters have to be enclosed in square brackets. An exception are single-element lists, where the brackets can be dropped. For example, let h1, h2, h3 be heuristic specifications, then [h1, h3], [h2] and h2 are examples for a list of heuristic specifications.

Parameters s and t are optional. s has the default value v1 and t the default value Enum1. t is an enumeration parameter and can only take the values listed (here Enum0, Enum1, Enum2). These values may also be passed by number, e.g. here t=Enum1 and t=1 are equivalent.

Some possible calls for this specification (with X and Xi having type_x):

• name(P, Q, R): s and v have their default values v1 and Enum1

• name(P, [Q], R): equivalent to previous call

• name(P, [Q1, Q2], R, t=Enum2): s has its default value v1

• name(t=1, r=R, qs=[Q1, Q2], s=S1, p=P) is equivalent to name(P, [Q1, Q2], R, S1, 1)

Notes

• Parameters of type bool are specified by strings true or false

• Parameters of type int can by specified by "infinity". This means that the parameter will take the value numeric_limits<int>::max(), which is usually equal to 2^31 - 1.

• not case-sensitive
• To get positions and keywords, run

./downward --help [Name]

Lists

List arguments have to be enclosed in square brackets now. E.g.,

./downward --heuristic "hff=ff()" --heuristic "hcea=cea()" \
            --search "lazy_greedy([hff, hcea], preferred=[hff, hcea])" \
            < output

instead of

./downward --heuristic "hff=ff()" --heuristic "hcea=cea()" \
            --search "lazy_greedy(hff, hcea, preferred=(hff, hcea))" \
            < output

Single element lists can be given without any brackets, e.g.

./downward --heuristic "hff=ff()" \
            --search "lazy_greedy(hff, preferred=hff)" \
            < output

Enumerations

Enumeration arguments can now be specified by name or by number (previously only by number), e.g.

selmax([h1,h2], classifier=AODE)

and

selmax([h1,h2], classifier=1)

are equivalent. To get enumeration names (and more), run

./downward --help [Name]   //e.g. with Name=selmax

Predefinitions

Often an object should be used for several purposes, e.g. a Heuristic or a LandmarkGraph. The most prevalent use case is a heuristic that is used for both the heuristic estimates and for its preferred operators. In this case, one should predefine the object.

Heuristic Predefinitions

Heuristics can be predefined using the search option --heuristic (see PlannerUsage#search).

--heuristic name=heuristic

• name (string): a name that should denote the heuristic

• heuristic (Heuristic): the heuristic

Landmark Predefinitions

If a set of landmarks should be used for several purposes, it can be predefined using the search option --landmarks (see PlannerUsage#search) to avoid duplicate work and memory usage.

--landmarks name=landmarks

• name (string): a name that should denote the set of landmarks

• landmarks (LandmarkGraph): the set of landmarks

Predefinition Example

Suppose I want to run GBFS with the lm_count heuristic (the inadmissible version), and then run another GBFS search with an admissible lm_count heuristic, using the h^m landmarks without discovering the landmarks twice.

 ./downward --landmarks "lm=lm_hm(m=2)"
            --search "iterated([
                              lazy_greedy(lmcount(lm)),
                              lazy_greedy(lmcount(lm,admissible=true))])" < output