Differences between revisions 34 and 66 (spanning 32 versions)

Usage

To run Fast Downward, use the fast-downward.py driver script. At minimum, you need to specify the PDDL input files and search options consisting of a search algorithm with one or more evaluator specifications. The driver script has many options to do things like running portfolios, running only the translation component of the planner, using a non-standard build, running a plan validator and various other things. To see the complete list of options, run

./fast-downward.py --help

If you want to run any of the planners based on Fast Downward that participated in IPC 2011, please also check IpcPlanners.

Caveats

The search options are built with flexibility in mind, not ease of use. It is very easy to use option settings that look plausible, yet introduce significant inefficiencies. For example, an invocation like ./fast-downward.py domain.pddl problem.pddl --search "lazy_greedy([ff()], preferred=[ff()])" looks plausible, yet is hugely inefficient since it will compute the FF heuristic twice per state. See the examples on the PlannerUsage page to see how to call the planner properly. If in doubt, ask.

Different builds

Different builds of Fast Downward (e.g. release vs. debug) are placed in different directories by the build script. Hence, several builds can coexist and fast-downward.py must be told which build to use. By default, the release build is used, which is also the default build produced by build.py. To use a different build, pass --build=<name> to the driver script. The parameter --debug is an alias for --build=debug --validate.

Note on IDE projects (Visual Studio, XCode): You can use the CMake build system to generate a project for you favourite IDE. These projects are what CMake calls "multi-config generators", i.e., they are created without fixing the build configuration. At build time, the IDE decides whether to do a debug or release build and creates subdirectories in the output folder. Use the full path to the binaries as the value of --build (e.g., --build=path/to/visual/studio/project/bin/Debug/).

Exit codes

The driver exits with 0 if no errors are encountered. Otherwise, it returns the exit code of the first component that failed. The exit codes are documented at ExitCodes.

LP support

Features that use an LP solver have a command-line option lpsolver to switch between different solver types. See issue752 and issue1076 for a discussion of the relative performance of CPLEX and SoPlex.

Note that SoPlex is not a MIP solver, so using it for configurations that require integer variables will result in an error. Please use CPLEX for such cases.

Examples

A* search

   1 # landmark-cut heuristic
   2  ./fast-downward.py domain.pddl task.pddl --search "astar(lmcut())"
   3 
   4 # iPDB heuristic with default settings
   5  ./fast-downward.py domain.pddl task.pddl --search "astar(ipdb())"
   6 
   7 # blind heuristic
   8  ./fast-downward.py domain.pddl task.pddl --search "astar(blind())"

Lazy greedy best-first search with preferred operators and the queue alternation method

   1 ## using FF heuristic and context-enhanced additive heuristic (previously: "fFyY")
   2  ./fast-downward.py domain.pddl task.pddl \
   3     --evaluator "hff=ff()" --evaluator "hcea=cea()" \
   4     --search "lazy_greedy([hff, hcea], preferred=[hff, hcea])" \
   5            
   6 
   7 ## using FF heuristic (previously: "fF")
   8  ./fast-downward.py domain.pddl task.pddl \
   9     --evaluator "hff=ff()" \
  10     --search "lazy_greedy([hff], preferred=[hff])" \
  11            
  12 
  13 ## using context-enhanced additive heuristic (previously: "yY")
  14  ./fast-downward.py domain.pddl task.pddl \
  15     --evaluator "hcea=cea()" \
  16     --search "lazy_greedy([hcea], preferred=[hcea])" \
  17

LAMA 2011

 ./fast-downward.py --alias seq-sat-lama-2011 domain.pddl task.pddl

runs the "LAMA 2011 configuration" of the planner. (Note that this is not really the same as "LAMA 2011" as it participated at IPC 2011 because there have been bug fixes and other changes to the planner since 2011. See IpcPlanners for more information.) To find out which actual search options the LAMA 2011 configuration corresponds to, check the source code of the src/driver/aliases.py module.

64-bit mode

Older planner versions built the planner in 32-bit mode by default because of lower memory consumption. As part of the meta issue issue213 we decreased the memory consumption of 64-bit builds to the point where there should be no difference between 32- and 64-bit builds for most configurations. Therefore, we use the native bitwidth of the operating system since January 2019.

-  ⇤ ← Revision 34 as of 2013-05-17 13:32:03 → 
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  Comment:
+   ← Revision 66 as of 2023-10-12 12:14:59 → ⇥
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  Comment: Remove link to deleted page ObtainingAndRunningFastDownward
-Deletions are marked like this.
+Additions are marked like this.
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-Running the planner is a three-step process as explained in Section 3 (pp. 202-203) of the [[http://www.jair.org/papers/paper1705.html|JAIR paper on Fast Downward]]. The following instructions show how to run these three steps, in sequence, assuming that the preprocessor and search component have been compiled and that you are currently located in the {{{src}}} directory.
+To run Fast Downward, use the {{{fast-downward.py}}} driver script. At minimum, you need to specify the PDDL input files and search options consisting of a [[Doc/SearchAlgorithm|search algorithm]] with one or more [[Doc/Evaluator|evaluator specification]]s. The driver script has many options to do things like running portfolios, running only the translation component of the planner, using a non-standard build, running a plan validator and various other things. To see the complete list of options, run

{{{
./fast-downward.py --help
}}}
-Line 9:
+Line 13:
-== Translator ==
+== Caveats ==
-Line 11:
+Line 15:
-{{{
translate/translate.py [DOMAIN] PROBLEM
+The '''search options''' are built with flexibility in mind, not ease of use. It is very easy to use option settings that look plausible, yet introduce significant inefficiencies. For example, an invocation like {{{ ./fast-downward.py domain.pddl problem.pddl --search "lazy_greedy([ff()], preferred=[ff()])"}}} looks plausible, yet is hugely inefficient since it will compute the FF heuristic twice per state. See the examples on the PlannerUsage page to see how to call the planner properly. If in doubt, ask.


== Different builds ==

Different builds of Fast Downward (e.g. release vs. debug) are placed in different directories by the build script. Hence, several builds can coexist and {{{fast-downward.py}}} must be told which build to use. By default, the {{{release}}} build is used, which is also the default build produced by {{{build.py}}}. To use a different build, pass {{{--build=<name>}}} to the driver script. The parameter {{{--debug}}} is an alias for {{{--build=debug --validate}}}.

'''Note on IDE projects (Visual Studio, XCode)''': You can use the CMake build system to generate a project for you favourite IDE. These projects are what CMake calls "multi-config generators", i.e., they are created without fixing the build configuration. At build time, the IDE decides whether to do a debug or release build and creates subdirectories in the output folder. Use the full path to the binaries as the value of {{{--build}}} (e.g., {{{--build=path/to/visual/studio/project/bin/Debug/}}}).

== Exit codes ==

The driver exits with 0 if no errors are encountered. Otherwise, it returns the exit code of the first component that failed. The exit codes are documented at ExitCodes. 

== LP support ==

Features that use an LP solver have a command-line option `lpsolver` to switch between different solver types. See [[http://issues.fast-downward.org/issue752|issue752]] and [[http://issues.fast-downward.org/issue1076|issue1076]] for a discussion of the relative performance of CPLEX and !SoPlex.

Note that !SoPlex is not a MIP solver, so using it for configurations that require integer variables will result in an error. Please use CPLEX for such cases.


== Examples ==

=== A* search ===

{{{#!highlight bash
# landmark-cut heuristic
 ./fast-downward.py domain.pddl task.pddl --search "astar(lmcut())"

# iPDB heuristic with default settings
 ./fast-downward.py domain.pddl task.pddl --search "astar(ipdb())"

# blind heuristic
 ./fast-downward.py domain.pddl task.pddl --search "astar(blind())"
-Line 15:
+Line 50:
- * `DOMAIN` (filename): PDDL domain file
 * `PROBLEM` (filename): PDDL problem file

If the domain file is not given, the planner will try to infer a likely name from the problem file name, using the conventions used at the various IPCs. (If in doubt if this will work for you, just try it out.)

Note: Creates a file called [[TranslatorOutputFormat#outputsas|output.sas]] (as well as [[TranslatorOutputFormat|test.groups]], all.groups, ...)
== Preprocessor ==

{{{
preprocess/preprocess < OUTPUT.SAS
}}}

 * `OUTPUT.SAS` (filename): translator output

Note: Creates a file called output 

<<Anchor(search)>>
== Search component ==

{{{
search/downward [OPTIONS] --search SEARCH < OUTPUT
}}}

 * `SEARCH` (SearchEngine): configuration of the search algorithm
 * `OUTPUT` (filename): preprocessor output
Options:
 * `--heuristic` [[ReusingHeuristics#predefinition|HEURISTIC_PREDEFINITION]]
   Predefines a heuristic that can afterwards be referenced by the name that is 
   specified in the definition.
 * `--random-seed` SEED
   Use random seed SEED

=== Exit codes ===
The list of '''exit codes''' for the search component is defined in [[http://hg.fast-downward.org/file/tip/src/search/utilities.h|src/search/utilities.h]] and explained below:

|| '''Code''' || '''Symbol''' || '''Meaning''' ||
|| 0 || EXIT_PLAN_FOUND || Solution found. ||
|| 1 || EXIT_CRITICAL_ERROR || Something went seriously wrong. E.g. an underlying library crashed. ||
|| 2 || EXIT_INPUT_ERROR || Wrong command line or SAS+ file. ||
|| 3 || EXIT_UNSUPPORTED || Requested unsupported feature. ||
|| 4 || EXIT_UNSOLVABLE || Task is provably unsolvable with current bound. Currently unused (see [[http://issues.fast-downward.org/issue377|issue377]]). ||
|| 5 || EXIT_UNSOLVED_INCOMPLETE || Search ended without finding a solution. ||
|| 6 || EXIT_OUT_OF_MEMORY || Memory exhausted. ||
|| 7 || EXIT_TIMEOUT || Timeout occured. Currently only returned by portfolios. ||
|| 8 || EXIT_TIMEOUT_AND_MEMORY || In portfolio configurations both timeouts and out-of-memory conditions occured. ||

=== Examples ===

A* search:

{{{#!highlight bash
# landmark-cut heuristic (previously configuration "ou")
 ./downward --search "astar(lmcut())" < output

# merge-and-shrink heuristic with default settings (previously configuration "oa50000")
 ./downward --search "astar(merge_and_shrink())" < output

# blind heuristic (previously configuarion "ob")
 ./downward --search "astar(blind())" < output
}}}

Lazy greedy best first search with preferred operators and the queue alternation method:
+=== Lazy greedy best-first search with preferred operators and the queue alternation method ===
-Line 80:
+Line 54:
- ./downward --heuristic "hff=ff()" --heuristic "hcea=cea()" \
            --search "lazy_greedy([hff, hcea], preferred=[hff, hcea])" \
            < output
+ ./fast-downward.py domain.pddl task.pddl \
    --evaluator "hff=ff()" --evaluator "hcea=cea()" \
    --search "lazy_greedy([hff, hcea], preferred=[hff, hcea])" \
-Line 85:
+Line 60:
- ./downward --heuristic "hff=ff()" \
            --search "lazy_greedy(hff, preferred=hff)" \
            < output
+ ./fast-downward.py domain.pddl task.pddl \
    --evaluator "hff=ff()" \
    --search "lazy_greedy([hff], preferred=[hff])" \
-Line 90:
+Line 66:
- ./downward --heuristic "hcea=cea()" \
            --search "lazy_greedy(hcea, preferred=hcea)" \
            < output
+ ./fast-downward.py domain.pddl task.pddl \
    --evaluator "hcea=cea()" \
    --search "lazy_greedy([hcea], preferred=[hcea])" \
-Line 95:
+Line 72:
-Q: I would like to see an example that uses the LAMA-FF Synergy feature.

A: See next question.

Q: Is it possible to make the planner behave like "old" LAMA (the IPC 2008 version)?

A: We recommend against doing that and suggest you run the planner in "LAMA 2011 mode" instead (see next question). Still, here is the information for a LAMA-2008-like configuration:

The following configuration has all the ingredients of LAMA: it uses the landmark and FF heuristics with synergy in a lazy alternation search with preferred operators for both heuristics, uses iterated search with the appropriate set of options, and performs LAMA's +1 action cost adjustment on the heuristic for problems with non-unit-cost actions. It also uses the same mechanism for computing landmarks as LAMA. (There are, however, a number of implementation differences that make the behaviour of the planner different from original LAMA, e.g. slightly different tie-breaking in the FF heuristic computation.)
+=== LAMA 2011 ===
-Line 106:
+Line 75:
-./downward --heuristic "hlm,hff=lm_ff_syn(lm_rhw(reasonable_orders=true,cost_type=2,lm_cost_type=2))"
           --search "iterated([lazy_greedy([hff,hlm],preferred=[hff,hlm]),
                               lazy_wastar([hff,hlm],preferred=[hff,hlm],w=5),
                               lazy_wastar([hff,hlm],preferred=[hff,hlm],w=3),
                               lazy_wastar([hff,hlm],preferred=[hff,hlm],w=2),
                               lazy_wastar([hff,hlm],preferred=[hff,hlm],w=1)],
                              repeat_last=true)" < output
+ ./fast-downward.py --alias seq-sat-lama-2011 domain.pddl task.pddl
-Line 115:
+Line 78:
-The following is the corresponding call to just find a first solution (i.e., not doing iterated search):
+runs the "LAMA 2011 configuration" of the planner. (Note that this is not really the same as "LAMA 2011" as it participated at IPC 2011 because there have been bug fixes and other changes to the planner since 2011. See IpcPlanners for more information.) To find out which actual search options the LAMA 2011 configuration corresponds to, check the source code of the {{{src/driver/aliases.py}}} module.
-Line 117:
+Line 80:
-{{{
 ./downward --heuristic "hlm,hff=lm_ff_syn(lm_rhw(reasonable_orders=true,cost_type=2,lm_cost_type=2))" 
            --search "lazy_greedy([hlm, hff], preferred=[hlm, hff])" 
            < output
}}}
+<<Anchor(64bit)>>
== 64-bit mode ==
-Line 123:
+Line 83:
-Q: What do I need to do to run LAMA 2011?

All planners in the Fast Downward family that participated in IPC 2011 use exactly the same code and only differ in the command-line options used for the search component of the planner. LAMA 2011 is a bit special in that it uses two different parameter settings depending on whether the input planning task uses unit-cost actions only or general action costs. To enable this automatic switching, run the planner with:

{{{
 ./downward ipc seq-sat-lama-2011 < output
}}}

To find out which actual search options this corresponds to, check the source code of the {{{downward}}} script. Please also check the comments below on 32-bit vs. 64-bit mode.

== 32-bit mode or 64-bit mode? ==

Our current codebase (as of November 2011) differs from the IPC versions of our planners in one way: by default, planner executables are compiled in 32-bit mode, while 64-bit was used at IPC 2011. The main differences between 32- vs. 64-bit mode are as follows:

 * 64-bit mode is faster than 32-bit mode (in our limited experiments typically by a factor of ~1.1)
 * 64-bit mode needs more memory than 32-bit mode (in our limited experiments typically by a factor of ~1.5)
 * 64-bit mode can use essentially unbounded amounts of memory, while 32-bit mode can only use 3 GB of user space memory (on typical Linux systems -- numbers may differ on other operating systems and depending on kernel options)

In our experiments, the memory advantage of 32-bit mode tends to outweigh the speed disadvantage, which is why we enable 32-bit mode by default. See http://issues.fast-downward.org/issue213 for details. However, for memory limits substantially beyond 4 GB, you should use 64-bit mode due to the address space limitations of 32-bit mode.

To enable 64-bit, change all occurrences of {{{-m32}}} in {{{src/search/Makefile}}} to {{{-m64}}}.
+Older planner versions built the planner in 32-bit mode by default because of lower memory consumption. As part of the meta issue [[http://issues.fast-downward.org/issue213|issue213]] we decreased the memory consumption of 64-bit builds to the point where there should be no difference between 32- and 64-bit builds for most configurations. Therefore, we use the native bitwidth of the operating system since January 2019.

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