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Before running Fast Downward, you must build it using the script.

To run Fast Downward, use the driver script. At minimum, you need to specify the PDDL input files and search options. 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

./ --help

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

Different builds

Different builds of Fast Downward (e.g. 32-bit vs. 64-bit, release vs. debug) are placed in different directories by the build script. Hence, several builds can coexist and must be told which build to use. By default, the release32 build is used, which is also the default build produced by To use a different build, pass --build=<name> to the driver script. The parameter --debug is an alias for --build=debug32 --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 translator exits with the following codes:




OK: translation successful


Critical error: something went wrong (e.g. translator bug, but also malformed PDDL input)


Usage error: wrong command line options

The search component and the portfolios can produce the exit codes listed below. In addition to the numbers we list the names of the exit codes as they are defined in src/search/utilities.h and driver/






Solution found



Something went wrong that should not have gone wrong (e.g. planner bug).



Wrong command line options or SAS+ file.



Requested unsupported feature.



Task is provably unsolvable with current bound. Currently unused (see issue377).



Search ended without finding a solution.



Memory exhausted.



Timeout occured. Only returned by portfolios.



In portfolio configurations both timeouts and out-of-memory conditions occurred.


   1 # landmark-cut heuristic
   2  ./ domain.pddl task.pddl --search "astar(lmcut())"
   4 # iPDB heuristic with default settings
   5  ./ domain.pddl task.pddl --search "astar(ipdb())"
   7 # blind heuristic
   8  ./ 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  ./ domain.pddl task.pddl \
   3     --heuristic "hff=ff()" --heuristic "hcea=cea()" \
   4     --search "lazy_greedy([hff, hcea], preferred=[hff, hcea])" \
   7 ## using FF heuristic (previously: "fF")
   8  ./ domain.pddl task.pddl \
   9     --heuristic "hff=ff()" \
  10     --search "lazy_greedy(hff, preferred=hff)" \
  13 ## using context-enhanced additive heuristic (previously: "yY")
  14  ./ domain.pddl task.pddl \
  15     --heuristic "hcea=cea()" \
  16     --search "lazy_greedy(hcea, preferred=hcea)" \

LAMA 2011

 ./ --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.) Please also check the comments below on 32-bit vs. 64-bit mode. To find out which actual search options the LAMA 2011 configuration corresponds to, check the source code of the src/driver/ module.

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:

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 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, use the build configurations release64 and debug64. For manual builds, call CMake with the option -DALLOW_64_BIT=TRUE and set up your build environment to compile for 64 bit (this depends on your system). For example, the following would work on Linux with gcc:

mkdir -p builds/manual_64_bit_build
cd builds/manual_64_bit_build
cmake -DALLOW_64_BIT=TRUE -DCMAKE_CXX_FLAGS="-m64" ../../src

Other questions?

Please get in touch! See the HomePage for various contact options.

FastDownward: PlannerUsage (last edited 2016-12-21 15:40:39 by MalteHelmert)