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Usage

Running the planner is a three-step process as explained in Section 3 (pp. 202-203) of the 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.

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

Driver script

We recommend using the src/fast-downward.py script for running Fast Downward. It supports running all three planner steps or a subset of them and automatically chooses the right steps depending on the given input. To see the list of options run

./fast-downward.py --help

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 and preprocessor exit with the following codes:

Code

Meaning

0

OK: translation/preprocessing successful

1

Critical error: something went wrong (e.g. translator/preprocessor bug).

2

Input 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 src/driver/portfolio_runner.py.

Code

Name

Meaning

0

EXIT_PLAN_FOUND

Translation successful/Preprocessing successful/Solution found

1

EXIT_CRITICAL_ERROR

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

2

EXIT_INPUT_ERROR

Wrong command line options or SAS+ file.

3

EXIT_UNSUPPORTED

Requested unsupported feature.

4

EXIT_UNSOLVABLE

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

5

EXIT_UNSOLVED_INCOMPLETE

Search ended without finding a solution.

6

EXIT_OUT_OF_MEMORY

Memory exhausted.

7

EXIT_TIMEOUT

Timeout occured. Only returned by portfolios.

8

EXIT_TIMEOUT_AND_MEMORY

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

Below are the instructions for running individual steps without the driver script.

Translator

translate/translate.py [DOMAIN] PROBLEM

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 output.sas.

Preprocessor

preprocess/preprocess < OUTPUT.SAS

Note: Creates a file called output.

Search component

search/downward OPTIONS < OUTPUT

Examples

   1 # landmark-cut heuristic
   2  ./fast-downward.py output --search "astar(lmcut())"
   3 
   4 # iPDB heuristic with default settings
   5  ./fast-downward.py output --search "astar(ipdb())"
   6 
   7 # blind heuristic
   8  ./fast-downward.py output --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 output \
   3     --heuristic "hff=ff()" --heuristic "hcea=cea()" \
   4     --search "lazy_greedy([hff, hcea], preferred=[hff, hcea])" \
   5            
   6 
   7 ## using FF heuristic (previously: "fF")
   8  ./fast-downward.py output \
   9     --heuristic "hff=ff()" \
  10     --search "lazy_greedy(hff, preferred=hff)" \
  11            
  12 
  13 ## using context-enhanced additive heuristic (previously: "yY")
  14  ./fast-downward.py output \
  15     --heuristic "hcea=cea()" \
  16     --search "lazy_greedy(hcea, preferred=hcea)" \
  17 

LAMA 2011

 ./fast-downward.py --alias seq-sat-lama-2011 output

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/aliases.py 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 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, compile the planner with the option DOWNWARD_BITWITH=64, e.g. by running

./build_all distclean
./build_all DOWNWARD_BITWIDTH=64

in the src directory. (If VAL is not currently compiled, the first line may give you an error, which you can ignore.)

Other questions?

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