Fast Downward has been in development since 2003, but the current timed release model was not adopted until 2019. This file documents the changes since the first timed release, Fast Downward 19.06.
For more details, check the repository history (https://github.com/aibasel/downward) and the issue tracker (https://issues.fast-downward.org). Repository branches are named after the corresponding tracker issues.
- add
dump_dot()
function tolandmark_graph.h
(copied from DALAI) - changed
dump_landmark_graph
to write tolandmarks.out
instead of printing when debug is toggled
Released on July 31, 2023.
Highlights:
-
The option parser of the search component has been completely reimplemented. The new option parser has full error reporting where the old code crashed on errors or silently accepted them. This is also an important stepping stone towards a future use of Fast Downward as a library. With the change, the
--evaluator
,--heuristic
and--landmarks
options are now deprecated in favor of a newlet
syntax. For example,--evaluator h=EVALUATOR --search SEARCH_ALGORITHM
is deprecated in favor of the expression
--search let(h, EVALUATOR, SEARCH_ALGORITHM)
-
We now compile using the C++20 standard, so all modern C++ features can be used as long as they are supported by all main compilers Fast Downward supports (see
README.md
). -
The linear programming and mixed integer programming features of Fast Downward now communicate directly with the LP/MIP solvers (SoPlex or CPLEX) rather than using the open solver interface OSI as an intermediary. This has also allowed us to move to more modern versions of these solvers.
-
The
lmcount
heuristic has been split into two separate heuristics calledlandmark_sum
andlandmark_cost_partitioning
. The former corresponds to the oldlmcount
with the optionadmissible=false
, the latter to the oldlmcount
with the optionadmissible=true
. -
The two new landmark heuristics (
landmark_sum
andlandmark_cost_partitioning
) compute preferred operators more efficiently than before. On average, this improves performance of LAMA-style planner configurations. -
The merge-and-shrink heuristic now stores labels and their transitions more efficiently, resulting in improved speed for merge-and-shrink heuristic construction.
-
The MIASM merge strategy for merge-and-shrink (more precisely, the
sf_miasm
merge scoring function) now has an option to cache scores. Caching is enabled by default and greatly speeds up construction of MIASM-based merge-and-shrink heuristics.
Details:
-
option parser: We implemented a new way of defining features and parsing them from the command line. The new parser now supports defining variables for features (heuristics and landmark graphs so far) as an expression within the option string. For example,
let(h, lmcut(), astar(h))
instantiates thelmcut
heuristic, binds it to the variableh
and uses it within theastar
search algorithm.This change to the parser is an important stepping stone towards solving a more general problem about how components interact. Details of the new parser are described in a blog article. We also improved the documentation of enum values. https://www.fast-downward.org/ForDevelopers/Blog/TheNewOptionParser https://issues.fast-downward.org/issue1073 https://issues.fast-downward.org/issue1040
-
translator, for developers: Unreachable atoms are now filtered from mutex groups in an earlier processing step than before. In a few domains this leads to a different finite-domain representation. We could remove an old hack related to static literals in goals, which is no longer necessary. We also added some type annotations, in particular to the core data structures. https://issues.fast-downward.org/issue1079
-
translator, for users: The change described in the previous entry can lead to Fast Downward producing a slightly different finite-domain representation in some cases.
-
search algorithms, for developers: Instead of "search engine" we now say "search algorithm" everywhere. Among other things, this affects source file and directory names, namespaces, class names. The change is also reflected in the documentation. https://issues.fast-downward.org/issue1099
-
Cartesian abstractions, for developers: The
cegar
directory and namespace have been renamed tocartesian_abstractions
to avoid confusion with CEGAR-based code in thepdbs
directory. https://issues.fast-downward.org/issue1098 -
landmarks: We replaced the
lmcount
heuristic with two new heuristics calledlandmark_sum
andlandmark_cost_partitioning
. No functionality is added or removed:landmark_sum
replaceslmcount
with the optionadmissible=false
andlandmark_cost_partitioning
replaceslmcount
with the optionadmissible=true
. https://issues.fast-downward.org/issue1071 -
landmarks: Refactor the computation of preferred operators in the landmark heuristics (
landmark_sum
andlandmark_cost_partitioning
). The change affects configurations based on LAMA that use preferred operators. While the semantics of the code did not change, the new version is slightly faster and can solve more tasks and/or improves plan quality in an anytime configuration within the same time limit. https://issues.fast-downward.org/issue1070 -
merge-and-shrink: Improve the way that labels and their transitions are stored. We removed the class
LabelEquivalenceRelation
. InsteadTransitionSystem
now handles locally equivalent labels itself using a newLocalLabelInfo
class and stores a mapping from global to local labels. Labels are now removed from label groups in batches during label reduction. With this change, we can now construct the atomic factored transition system (and the overall heuristic) in significantly more cases, reducing both memory usage and construction time. https://issues.fast-downward.org/issue927 -
merge-and-shrink: The MIASM scoring function (feature
sf_miasm
) now has an option to cache scores for merge candidates, enabled by default. This greatly decreases computation time of M&S abstractions with this scoring function. https://issues.fast-downward.org/issue1092 -
pattern databases: The pattern generators
cegar_pattern
andrandom_pattern
now correctly support fractional values for themax_time
parameter. Previously the fractional part was silently ignored. For example a timeout of 7.5 seconds was treated as 7 seconds. -
pattern databases, for developers: We split off the computation of pattern databases from the
PatternDatabase
class.PatternDatabase
now stores pattern,hash_multipliers
andnum_states
in a new classProjection
, used for ranking and unranking. PDBs can be computed via a function which uses an internal classPatternDatabaseFactory
. Abstract operators live in their own files now, similar toMatchTree
. Performance does not change due to this issue. https://issues.fast-downward.org/issue1019 -
LP/MIP solvers: So far, we used the open solver interface OSI to communicate with MIP and LP solvers. We now replaced this with our own interface to have more direct control and fewer external dependencies. We now support CPLEX 22.1.1 and SoPlex from their current main branch (released versions <= 6.0.3 are incompatible with C++20). We removed the solver options for CLP and Gurobi in the process: CLP has much worse performance than SoPlex, which is also open source, while Gurobi was never practically possible to compile with, as we did not have a CMake find script for it. Performance with CPLEX increases in MIP configurations and stays roughly the same in LP configurations. Performance with SoPlex increases for potential heuristics and decreased slightly in other configurations. Our Windows builds forced static linking because of OSI. With OSI removed, they no longer do. https://issues.fast-downward.org/issue1076 https://issues.fast-downward.org/issue1093 https://issues.fast-downward.org/issue1095
-
LP/MIP solvers, for developers: Previously, LP solvers could crash if a constraint included multiple terms for the same variable. We now protect against this with an assertion in debug mode. The change has no effect on release builds. https://issues.fast-downward.org/issue1088
-
build: The build script now performs the requested builds in the given order. For example,
./build.py debug release
will perform a debug build and then a release build. Previously, the order was arbitrary, depending on Python dictionary order. https://issues.fast-downward.org/issue1086 -
C++ standard: We now compile the planner using the C++20 standard. We added tests for GCC 12 and clang 14 but dropped tests for GCC 9, clang 10, and clang 11.
The minimal supported compilers are now:
- g++-10
- clang-12
- MSVC 19.34
- AppleClang 13.0
Language features supported by all of these compilers may now be used in the planner. For a list of such features and more details, see the issue tracker. The list includes
std::optional
, so we removed the implementation ofoptional
insrc/search/ext
. https://issues.fast-downward.org/issue1028 https://issues.fast-downward.org/issue1094 -
Windows build: We now enable more compiler warnings on Windows builds. In detail, we no longer ignore warnings C4800, C4512, C4706, C4100, C4127, C4309, C4702, C4239, C4996, and C4505 on Windows builds as they no longer occur in our code. Warnings in GitHub actions are now also treated as errors in Windows builds. https://issues.fast-downward.org/issue565
-
infrastructure: We fixed a problem with using CPLEX in the GitHub action builds on Ubuntu. https://issues.fast-downward.org/issue1093
-
infrastructure: We update the version of uncrustify used to fix code formatting. Instructions on how to install the new version can be found on the wiki: https://www.fast-downward.org/ForDevelopers/Uncrustify. https://issues.fast-downward.org/issue1090
Released on December 15, 2022.
Highlights:
-
We now test more recent versions of Ubuntu Linux (22.04 and 20.04), macOS (11 and 12) and Python (3.8 and 3.10).
-
Most search algorithms are now faster. We fixed a performance problem related to state pruning, which also affected search configurations that did not explicitly select a pruning method.
-
All landmark factories now respect action costs. Previously, this was only the case when using admissible landmark heuristic or when using the
lm_rhw
landmark factory. Note that ignoring action costs (i.e., the old behaviour for landmark factories other thanlm_rhw
) often finds plans faster and is still possible with theadapt_costs
transformation.
Details:
-
driver: Planner time is now logged in a consistent format. Previously, it would sometimes be logged in scientific notation.
-
driver, for developers: Skip pycache directory when collecting portfolios. https://issues.fast-downward.org/issue1057
-
translator: Allow importing pddl_parser without parsing arguments from command line. https://issues.fast-downward.org/issue1068
-
pruning methods: Fix a performance regression caused by spending too much time measuring elapsed time. This is now only done at verbosity level
verbose
or higher. Verbosity level parameter added to all pruning methods. https://issues.fast-downward.org/issue1058 Note that most search algorithms in Fast Downward always use a pruning method (a trivial method pruning nothing is used by default) and were therefore affected by this performance problem. -
pruning methods, for developers: We cleaned up the internal structure of stubborn set pruning. https://issues.fast-downward.org/issue1059
-
landmarks: All landmark factories are now sensitive to action costs. https://issues.fast-downward.org/issue1009 When using the
lmcount
heuristic in inadmissible mode (optionadmissible=false
), previously only thelm_rhw
landmark factory considered action costs. Now, all landmark factories do. (This was already the case withadmissible=true
.) Experiments show that ignoring action costs is often beneficial when we are more interested in planner speed or coverage than plan quality. This can be achieved by using the optiontransform=adapt_costs(ONE)
. -
landmarks: Reduce verbosity of h^m landmarks. The
lm_hm
landmark factory is now less verbose by default. Use verbosity levelverbose
or higher to enable the previous output. -
infrastructure: Update tested OS versions and clang-tidy version. https://issues.fast-downward.org/issue1067
- The tested Ubuntu versions are now 22.04 and 20.04.
- The tested macOS versions are now macOS 11 and macOS 12.
- The tested Windows version remains Windows 10.
- We now test Python 3.10 (Ubuntu 22.04, macOS 12) and Python 3.8 (Ubuntu 20.04, macOS11, Windows 10).
- We now use clang-tidy-12.
See
README.md
for details.
-
infrastructure: Update delete-artifact version number in GitHub action, update zlib version in Windows build.
Released on September 15, 2022.
This is a bugfix release fixing two serious bugs in Fast Downward 22.06:
-
Driver configurations relying on certain kinds of time limits (using the
--overall-time-limit
option or portfolios) crashed when using Python 3.10. https://issues.fast-downward.org/issue1064 -
Using post-hoc optimization constraints (
pho_constraints
) caused crashes (segmentation faults) or other undefined behavior. https://issues.fast-downward.org/issue1061
Released on June 16, 2022.
Highlights:
-
We fixed a bug in the translator component that could lead to incorrect behavior in tasks where predicates are mentioned in the goal that are not modified by any actions.
-
Various speed improvements to landmark factories. This is part of a larger ongoing clean-up of the landmark code.
-
More informative output, and more control over the output. The driver now prints the total runtime of all components. For many planner components, including all heuristics, the verbosity level can now be configured individually.
Details:
-
translator: Fix a bug where the translator would not check goal conditions on predicates that are not modified by actions. https://issues.fast-downward.org/issue1055
-
driver: Print overall planner resource limits and overall planner runtime on Linux and macOS systems. https://issues.fast-downward.org/issue1056
-
logging: verbosity option for all evaluators https://issues.fast-downward.org/issue921 All evaluators and heuristics now have their own configurable logger and no longer use g_log. These loggers have a verbosity option, which allows choosing between silent, normal, verbose and debug for all instances of evaluators created on the command line.
-
landmarks: Speed up landmark generation time by 10-20% for
lm_rhw
,lm_zg
, andlm_exhaust
by avoiding unnecessary computations in the landmark exploration. https://issues.fast-downward.org/issue1044 -
landmarks: Speed up landmark generation time by 5-15% for
lm_rhw
,lm_zg
, andlm_exhaust
by computing reachability in the landmark exploration as boolean information instead of (unused) integer cost/level information. https://issues.fast-downward.org/issue1045 -
landmarks: Improve landmark dead-end detection so that relevant static information is only computed once, instead of at every state evaluation. https://issues.fast-downward.org/issue1049
-
infrastructure: Upgrade GitHub Actions to Windows Server 2019 (Visual Studio Enterprise 2019) and Windows Server 2022 (Visual Studio Enterprise 2022). Remove Windows Server 2016, because GitHub Actions no longer support it. https://issues.fast-downward.org/issue1054
-
infrastructure: Run GitHub Actions only for the following branches:
main
,issue*
,release-*
. https://issues.fast-downward.org/issue1027
Released on February 16, 2022.
Highlights:
-
Fast Downward now has a logo!
-
We added new methods for generating patterns and pattern collections based on counterexample-guided abstraction refinement and a new highly random method for generating individual patterns based on the causal graph. These methods are due to Rovner et al. (ICAPS 2019).
-
The operator-counting heuristic now has an option to use integer operator counts rather than real-valued operator counts. This makes the heuristic more accurate at a vastly increased computational cost (not generally recommended, but very useful for targeted experiments). We added a new constraint generator for Imai and Fukunaga's delete relaxation constraints (JAIR 2015). With the right option settings, the operator-counting heuristic with this new constraint generator results in the optimal delete relaxation heuristic h+.
-
Pruning methods now have a different interface. The mechanism to disable pruning automatically after a number of expansions that resulted in little pruning is now implemented as its own pruning method that wraps another pruning method. Be careful that the old syntax is still accepted by the planner, but the options that limit pruning are ignored. (This is due to an option parser bug; a fix is in the works.)
-
In our ongoing efforts to improve the landmark code, the landmark factories and landmark-count heuristic received a major overhaul. We removed irrelevant options for landmark factories, decoupled the computation of reasonable orders from landmark generation, made many internal code and data structure changes to make the code nicer to work with and fixed several long-standing bugs.
-
All pattern generators and pattern collection generators now have controllable verbosity. Similar changes to other components of the planner are planned. This is part of a general effort to make logging more configurable.
-
For developers: The internal representation of states has been overhauled, resolving the confusion between the previous classes
GlobalState
andState
.
Details:
-
new Fast Downward logo https://issues.fast-downward.org/issue1024 You can see the logo in the README file on https://github.com/aibasel/downward. Check out https://www.fast-downward.org/ForDevelopers/Blog/LogoDesigns for alternative suggestions including the ever so popular "truck falling down the hill" logo.
-
fast-downward.py main script: The script now automatically finds domain files
<taskfile>-domain.<ext>
for task files called<taskfile>.<ext>
https://issues.fast-downward.org/issue1033 -
pdbs: Integrate the Rovner et al. pattern generation methods based on CEGAR. https://issues.fast-downward.org/issue1007
-
pdbs: Integrate the Rovner et al. random pattern generation methods. https://issues.fast-downward.org/issue1008
-
pdbs: All pattern (collection) generators now have an option
verbosity
to set the desired level of output. https://issues.fast-downward.org/issue1043 Internally, generators now use their own logger rather than g_log. -
pdbs, for developers: Replace size_t by int for abstract state hashes in PDB-related code. https://issues.fast-downward.org/issue1018
-
LP/IP: Support integer variables in linear programs. https://issues.fast-downward.org/issue891 https://issues.fast-downward.org/issue1048 You can now use the LP solver interface to solve mixed integer programs. In particular, the operator-counting heuristics now have an option
use_integer_operator_counts
that improves the heuristic value by forcing operator counts to take integer values. Solving a MIP is NP-hard and usually takes much longer than solving the corresponding LP. -
LP/IP: Delete-relation constraints can now be used in the operator-counting framework. The constraints defined by Imai and Fukunaga (JAIR 2015) encode different relaxations of the delete-relaxation heuristic. For details, see https://www.fast-downward.org/Doc/ConstraintGenerator#Delete_relaxation_constraints https://issues.fast-downward.org/issue983
-
LP/IP: Fix a bug which induced inadmissible heuristic values when solving MIPs. This only occurred for operator-counting heuristics with integer variables and very large heuristic values (at least 10,000). https://issues.fast-downward.org/issue983
-
LP/IP, for developers: Add debugging methods to LP solver interface. https://issues.fast-downward.org/issue960 You can now assign names to LP variables and constraints for easier debugging. Since this incurs a slight runtime penalty, we recommend against using this feature when running experiments.
-
LP/IP, for developers: Debug builds with LP solvers vs. the
_GLIBCXX_DEBUG
flag. https://issues.fast-downward.org/issue982 Previously, we used the flag_GLIBCXX_DEBUG
in debug builds for additional checks. This makes the binary incompatible with external libraries such as LP solvers. The flag is now disabled by default. If no LP solvers are present or LP solvers are disabled, it can be enabled by setting the CMake optionUSE_GLIBCXX_DEBUG
. The build configurationsdebugnolp
andreleasenolp
have been removed, and the build configurationglibcxx_debug
has been added. -
pruning: New
LimitedPruning
class replaces previous limitation options of individual pruning methods. https://issues.fast-downward.org/issue1042 For example, the old command line--search "astar(lmcut(),pruning=atom_centric_stubborn_sets(min_required_pruning_ratio=0.2,expansions_before_checking_pruning_ratio=1000))"
is now expressed as--search "astar(lmcut(),pruning=limited_pruning(pruning=atom_centric_stubborn_sets(),min_required_pruning_ratio=0.2,expansions_before_checking_pruning_ratio=1000))
-
landmarks: Replace landmark factory option
reasonable_orders
by the new landmark factorylm_reasonable_orders_hps
. https://issues.fast-downward.org/issue995 For example, the old command line--evaluator hlm=lmcount(lm_factory=lm_rhw(reasonable_orders=true))
is now expressed as--evaluator hlm=lmcount(lm_factory=lm_reasonable_orders_hps(lm_rhw()))
-
landmarks: Replace landmark factory option
no_orders
by the new optionuse_orders
with the opposite meaning. https://issues.fast-downward.org/issue995 -
landmarks: Removed landmark factory options that have no effect. https://issues.fast-downward.org/issue995 Removed options:
lm_exhaust
:disjunctive_landmarks
,conjunctive_landmarks
lm_hm
:disjunctive_landmarks
,only_causal_landmarks
lm_merged
:disjunctive_landmarks
,conjunctive_landmarks
,only_causal_landmarks
lm_rhw
:conjunctive_landmarks
,reasonable_orders
lm_zg
:disjunctive_landmarks
,conjunctive_landmarks
,only_causal_landmarks
-
landmarks: Fix a bug where
lm_rhw
would compute wrong greedy-necessary orderings in certain cases. https://issues.fast-downward.org/issue1004 -
landmarks: Fix a bug where the
lm_rhw
,lm_zg
andlm_exhaust
landmark factories used an overly optimistic approximation of relaxed reachability for planning tasks with conditional effects. This change can lead to more generated landmarks and landmark orderings in such tasks. https://issues.fast-downward.org/issue1041 -
landmarks: Fix a bug where the Zhu/Givan landmark factory caused a crash on relaxed unsolvable tasks due to an empty landmark graph. https://issues.fast-downward.org/issue998
-
landmarks: Fix a bug where cycles of natural orderings resulted in crashes in the landmark factories. This could only happen in unsolvable planning tasks. https://issues.fast-downward.org/issue937
-
landmarks: Fix a failing assertion in the
lm_rhw
landmark factory triggered by certain unsolvable tasks. https://issues.fast-downward.org/issue467 -
landmarks, for developers: Clean up the code of
LandmarkGraph
. Some of the public methods were renamed. This class will undergo further changes in the future. https://issues.fast-downward.org/issue989 -
landmarks, for developers: Separate the functionality of landmarks from the functionality of landmark nodes by introducing a new
Landmark
class. https://issues.fast-downward.org/issue999 -
landmarks, for developers: Move functionality used during search away from
LandmarkGraph
, making the landmark graph constant after creation. https://issues.fast-downward.org/issue988 https://issues.fast-downward.org/issue1000 -
landmarks, for developers: Introduce new class
LandmarkFactoryRelaxation
for landmark factories based on delete relaxation. Move usage of exploration object to subclasses of the landmark factory base class. https://issues.fast-downward.org/issue990 -
build: The build system now prefers compilers
cc
/c++
found on the path overgcc
/g++
. As before, environment variablesCC
/CXX
can be used to override this choice. https://issues.fast-downward.org/issue1031 -
build: Only build configurations defined in
build_configs.py
are loaded in thebuild.py
script. https://issues.fast-downward.org/issue1016 -
for developers: Add option to use a local (configurable) logger instead of the global one. https://issues.fast-downward.org/issue964 Classes which want to configure the logger (currently only the verbosity level can be configured) should now use the functions
add_log_options_to_parser
andget_log_from_options
to obtain their local log object. -
for developers: Unify the
State
andGlobalState
classes. https://issues.fast-downward.org/issue348 We unified the classesGlobalState
andState
into a new class also calledState
. This removed a lot of code duplication and hacks from the code. A description of the new class can be found in the wiki: https://www.fast-downward.org/ForDevelopers/Blog/ADeeperLookAtStates -
for developers: Change public interface of generation of random ints and doubles in the
RandomNumberGenerator
class. https://issues.fast-downward.org/issue1026 -
for developers: Use
RandomNumberGenerator
class inVariableOrderFinder
. https://issues.fast-downward.org/issue1032 -
infrastructure: Add support for GitHub actions. https://issues.fast-downward.org/issue940
-
infrastructure: Add CPLEX support to our GitHub Actions for Windows. https://issues.fast-downward.org/issue1005
-
infrastructure: Decide on rules regarding software support and improve GitHub actions accordingly. https://issues.fast-downward.org/issue1003
Released on July 26, 2020.
Highlights:
-
The Singularity and Docker distributions of the planner now include LP support using the SoPlex solver out of the box. Thank you to ZIB for their solver and for giving permission to include it in the release.
-
The Vagrant distribution of the planner now includes LP support using the SoPlex and/or CPLEX solvers out of the box if they are made available when the virtual machine is first provisioned. See https://www.fast-downward.org/QuickStart for more information.
-
A long-standing bug in the computation of derived predicates has been fixed. Thanks to everyone who provided bug reports for their help and for their patience!
-
A new and much faster method for computing stubborn sets has been added to the planner.
-
The deprecated merge strategy aliases
merge_linear
andmerge_dfp
have been removed.
Details:
-
Fix crash of
--show-aliases
option of fast-downward.py. -
Fix incorrect computation of derived predicates. https://issues.fast-downward.org/issue453 Derived predicates that were only needed in negated form and cyclically depended on other derived predicates could be computed incorrectly.
-
Integrate new pruning method
atom_centric_stubborn_sets
. https://issues.fast-downward.org/issue781 We merged the code for the SoCS 2020 paper "An Atom-Centric Perspective on Stubborn Sets" (https://ai.dmi.unibas.ch/papers/roeger-et-al-socs2020.pdf). See https://www.fast-downward.org/Doc/PruningMethod. -
Remove deprecated merge strategy aliases
merge_linear
andmerge_dfp
. The deprecated merge strategy aliasesmerge_linear
for linear merge strategies andmerge_dfp
for the DFP merge strategy are no longer available. See https://www.fast-downward.org/Doc/MergeStrategy for equivalent command line options to use these merge strategies. -
For developers: use global logging mechanism for all output. https://issues.fast-downward.org/issue963 All output of the planner is now handled by a global logging mechanism, which prefaces printed lines with time and memory information. For developers, this means that output should no longer be passed to
cout
but toutils::g_log
. Further changes to logging are in the works. -
For developers: store enum options as enums (not ints) in Options objects. https://issues.fast-downward.org/issue962
-
For developers: allow creating Timers in stopped state. https://issues.fast-downward.org/issue965
Released on December 20, 2019.
Highlights:
-
Fast Downward no longer supports Python 2.7, which reaches its end of support on January 1, 2020. The minimum supported Python version is now 3.6.
-
Fast Downward now supports the SoPlex LP solver.
Details:
-
general: raise minimum supported Python version to 3.6 https://issues.fast-downward.org/issue939 Fast Downward now requires Python 3.6 or newer; support for Python 2.7 and Python 3.2-3.5 has been dropped. The main reason for this change is Python 2 reaching its end of support on January 1, 2020. See https://python3statement.org/ for more background.
-
LP solver: add support for the solver SoPlex https://issues.fast-downward.org/issue752 The relative performance of CPLEX and SoPlex depends on the domain and configuration with each solver outperforming the other in some cases. See the issue for a more detailed discussion of performance.
-
LP solver: add support for version 12.9 of CPLEX https://issues.fast-downward.org/issue925 Older versions are still supported but we recommend using 12.9. In our experiments, we saw performance differences between version 12.8 and 12.9, as well as between using static and dynamic linking. However, on average there was no significant advantage for any configuration. See the issue for details.
-
LP solver: update build instructions of the open solver interface https://issues.fast-downward.org/issue752 https://issues.fast-downward.org/issue925 The way we recommend building OSI now links dynamically against the solvers and uses zlib. If your existing OSI installation stops working, try installing zlib (sudo apt install zlib1g-dev) or re-install OSI (https://www.fast-downward.org/LPBuildInstructions).
-
merge-and-shrink: remove trivial factors https://issues.fast-downward.org/issue914 When the merge-and-shrink computation terminates with several factors (due to using a time limit), only keep those factors that are non-trivial, i.e., which have a non-goal state or which represent a non-total function.
-
tests: use pytest for running most tests https://issues.fast-downward.org/issue935 https://issues.fast-downward.org/issue936
-
tests: test Python code with all supported Python versions using tox https://issues.fast-downward.org/issue930
-
tests: adjust style of Python code as suggested by flake8 and add this style check to the continuous integration test suite https://issues.fast-downward.org/issue929 https://issues.fast-downward.org/issue931 https://issues.fast-downward.org/issue934
-
scripts: move Stone Soup generator scripts to separate repository at https://github.com/aibasel/stonesoup. https://issues.fast-downward.org/issue932
Released on June 11, 2019. First time-based release.