Introduction

This artifact contains all tools and benchmarks that were used to obtain the experimental results in the paper "On Dependent Variables in Reactive Synthesis". The tool DepSynt developed as part of this work builds on the publicly available and widely used automata manipulation and synthesis library Spot. Our comparisons are done with the best performing entries in SYNTCOMP 2023 competition. Four of these entries are implemented in Spot. The fifth one, named Strix, is not implemented in Spot, but is provided as part of this artifact for the sake of completeness. Our artifact contains instructions on how to install our tool and competing ones, and also describes how to run our tool on individual benchmarks and on a batch of them. We also describe how to compare the performance of DepSynt with the five competing tools. The runtimes reported in the paper are obtained from a high performance computing cluster, and may differ from those obtained from the TACAS Artifact Evaluation VM. However, the relative trends should be the same as those reported in the paper.

Hyperlink to Artifact

Link to the Github repository: https://github.com/eliyaoo32/DepSynt

Building & Installation

• The build process might take 20 minutes approximately.
• Assuming that you have the TACAS24' VM, you can build DepSynt by running the following commands:

chmod +x ./build.sh
sudo ./build.sh

You can verify that the installation was successful by running the following command:

./depsynt --help

The expected output should be:

Tool to synthesis LTL specification using dependencies and Unates concept:
  -f [ --formula ] arg     LTL formula
  -o [ --output ] arg      Output variables
  -i [ --input ] arg       Input variables
  -v [ --verbose ]         Verbose messages
  --measures-path arg
  --model-name arg         Unique model name of the specification
  --dependency-timeout arg Timeout for finding dependencies in milliseconds, if
                           0 then the process skips finding dependencies
  --merge-strategies       Should merge the independent and dependent 
                           strategies
  --model-checking         Should apply model checking to the synthesized 
                           strategy
  --measure-bdd            Should measure the BDD size of NBAs

Benchmarks

The 1,141 benchmarks from SYNTCOMP are available in two formats:

1. TLSF - The benchmarks are located in the scripts/benchmarks/tlsf folder.

2. LTL Formula - The benchmarks are located in the scripts/benchmarks-ltl folder.

We have converted from TLSF specification to LTL using the public available tool Syfco (Included in this artifact).

Usage

How to run DepSynt on a specific benchmark

For example, suppose we want to run DepSynt on the benchmark ltl2dpa10 which has input variables b,a and output variables p2,p1,p0. LTL formula corresponding to this benchmark is:

((G (((((p0) && (! (p1))) && (! (p2))) || (((! (p0)) && (p1)) && (! (p2)))) || (((! (p0)) && (! (p1))) && (p2)))) && (((F (G (a))) || (G (F (b)))) <-> ((G (F (p0))) || ((G (F (p2))) && (! (G (F (p1))))))))

We want to limit the dependency finding process to 10 seconds (10,000 milliseconds).

The following command should then be executed:

./depsynt --model-name="ltl2dpa10" --input="b,a" --output="p2,p1,p0" --dependency-timeout=10000 --formula="((G (((((p0) && (! (p1))) && (! (p2))) || (((! (p0)) && (p1)) && (! (p2)))) || (((! (p0)) && (! (p1))) && (p2)))) && (((F (G (a))) || (G (F (b)))) <-> ((G (F (p0))) || ((G (F (p2))) && (! (G (F (p1))))))))"

The expected output for realizable specification like the above one is:

Circuit in AIG format of mealy machine representing strategy for independent outputs.
Circuit in AIG format of mealy machine representing strategy for dependent outputs.
Performance metrcies and related information like count of dependency / dependent variables in JSON format.

In case of unrealizable specification, the expected output is:

UNREALIZABLE
Performance metrcies and related information like count of dependency / dependent variables in JSON format.

How to run Ltlsynt (Competing tool) on a specific benchmark

Ltlsynt is one of the winning entries in SYNTCOMP 2023 and is based on Spot library. Ltlsynt can be run with a variety of algorithms. For our experimental comparison we used the algorithms denoted by sd,ds,lar,acd.

The algorithm can be specified using the following command line option:

--algo=sd|ds|lar|acd

To run Ltlsynt on the same benchmark ltl2dpa10 as above with algo acd, use the following command:

ltlsynt --aiger --algo=acd --outs="p2,p1,p0" --ins="b,a" --formula="((G (((((p0) && (! (p1))) && (! (p2))) || (((! (p0)) && (p1)) && (! (p2)))) || (((! (p0)) && (! (p1))) && (p2)))) && (((F (G (a))) || (G (F (b)))) <-> ((G (F (p0))) || ((G (F (p2))) && (! (G (F (p1))))))))" 

The expected output of realizable specification is:

REALIZABLE
Circuit in AIG format of mealy machine representing strategy for the specification.

In the case of unrealizable specification, the expected output is:

UNREALIZABLE

How to run Strix (Competing tool) on a specific benchmark

Strix is one of the winning entries in SYNTCOMP 2023.

To run Strix on the same benchmark ltl2dpa10, use the following command:

./strix --ins="b,a" --outs="p2,p1,p0" -o aag -f "((G (((((p0) && (! (p1))) && (! (p2))) || (((! (p0)) && (p1)) && (! (p2)))) || (((! (p0)) && (! (p1))) && (p2)))) && (((F (G (a))) || (G (F (b)))) <-> ((G (F (p0))) || ((G (F (p2))) && (! (G (F (p1))))))))"

The expected output of realizable specification is:

REALIZABLE
Circuit in AIG format of mealy machine representing strategy for the specification.

In the case of unrealizable specification, the expected output is:

UNREALIZABLE

How to run comparison between DepSynt, Ltlsynt and Strix on multiple benchmarks together

• This process can take very long time on the VM depending on the benchmarks size.
• All the execution have to be run sequentially on the VM.
• Note that the results reported in the paper were obtained on a high performance computing cluster with parallel runs using Slurm which is reliable in terms time and resources per tool.
• These times may differ from those obtained from the TACAS Artifact Evaluation VM. However, the relative trends should be the same as those reported in the paper.

For example, suppose we want to run DepSynt, Ltlsynt and Strix on the benchmarks ltl2dpa16,ltl2dpa10,Increment together, limiting each benchmark on each tool for 10 seconds. The following command should then be executed:

python3 ./run-benchmarks.py --timeout=10000 --benchmarks=ltl2dpa16,ltl2dpa10,Increment

Important notes:

• The benchmarks name are case-sensitive, the same as appears in the folder scripts/benchmarks-ltl.
• The timeout is in milliseconds.
• The script outputs in CSV with the headers: benchmark, depsynt_status, depsynt_duration, strix_status, strix_duration, ltlsynt_status, ltlsynt_duration.
• You can write the CSV to file using the --output-csv option:

python3 ./run-benchmarks.py --output-csv=./results.csv --timeout=10000 --benchmarks=ltl2dpa16,ltl2dpa10,Increment

If you want to apply this script on all the benchmarks, you can set the --benchmarks=* option (This process may take days):

python3 ./run-benchmarks.py --benchmarks=* --timeout=10000

Code Overview

DepSynt is a tool to synthesize a reactive synthesis specification exploting dependent variables.

• Entrypoint for the tool is bins/synthesis.cpp

The tool has the following steps:

1. Construct NBA A of the LTL specification (Implemented by Spot)
2. Find a maximal set of dependent variables (Source code: src/findDeps/find_deps_by_automaton.cpp)
3. If no dependent variable was found, synthesis NBA A using Spot and close the process.
4. Construct NBA A' which is a clone of A with the dependent variables removed. (Source code: src/synthesis/synthesis_utils.cpp)
5. Synthesis a strategy as AIG for A' using Spot. (Source code: src/synthesis/synthesis_utils.cpp). 5.1. If A' is not realizable, the specification is not realizable and the process is closed.
6. Synthesis a strategy as AIG format for dependent variables (Source code: src/synthesis/dependents_synthesiser.cpp)
7. (If requested) Merge the 2 strategies (Source code: src/synthesis/merge_strategies.cpp) 7.1. This step uses AIGER and BLIF format to merge the strategy. 7.2. ABC is used to balance and final strategy.
8. (If requested) Model checking the synthesized strategy - by checking if the negation of the specification intersects with the language of strategy.

Please notice: We have some additional experimental features, the code for which may be found in the directory "src/unates". The files in this directory can be ignored for purposes of the experiments reported in the paper. We included these files to provide an exact copy of the source code base that was used to build our tool and conduct experiments reported in the paper.