This is a fork of Fast Downward extended with an implementation of the hCFF heuristic and online refinement of explicit conjunctions. This implementation has been used for experiments in the following literature:

• J. Hoffmann and M. Fickert: Explicit Conjunctions w/o Compilation: Computing hFF(PiC) in Polynomial Time (ICAPS'15)
• M. Fickert, J. Hoffmann, and M. Steinmetz: Combining the Delete Relaxation with Critical-Path Heuristics: A Direct Characterization (JAIR'16)
• M. Fickert and J. Hoffmann: Complete Local Search: Boosting Hill-Climbing through Online Relaxation Refinement (ICAPS'17)
• M. Fickert and J. Hoffmann: Ranking Conjunctions for Partial Delete Relaxation Heuristics in Planning (SOCS'17)
• M. Fickert: Making Hill-Climbing Great Again through Online Relaxation Refinement and Novelty Pruning (SOCS'18)
• M. Fickert: A Novel Lookahead Strategy for Delete Relaxation Heuristics in Greedy Best-First Search (ICAPS'20)
• M. Fickert and J. Hoffmann: Online Relaxation Refinement for Satisficing Planning: On Partial Delete Relaxation, Complete Hill-Climbing, and Novelty Pruning (JAIR'22)

It is also the code base of OLCFF and parts of Saarplan; both planners competed in the International Planning Competition 2018.

The hCFF heuristic and online-refinement search engines are implemented in src/search/conjunctions. The best-performing configurations of RHC, RHC-SC, and GBFS-SCL from the JAIR'22 paper have corresponding aliases (see driver/aliases.py), so they can be run as follows:

./fast-downward.py --alias RHC task.pddl
./fast-downward.py --alias RHC-SC task.pddl
./fast-downward.py --alias GBFS-SCL task.pddl

The jair22-data.tar.xz file contains the raw data from the JAIR'22 experiments (in the Downward Lab JSON format).

The code also contains a copy of the h2 preprocessor (Alcazar and Torralba, ICAPS'15), which can be enabled by prepending the --transform-task=preprocess driver option.

Fast Downward is a domain-independent planning system.

For documentation and contact information see http://www.fast-downward.org/.

The following directories are not part of Fast Downward as covered by this license:

• ./src/search/ext

For the rest, the following license applies:

Fast Downward is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.

Fast Downward is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>.