79 research outputs found
Compositional Algorithms for Succinct Safety Games
We study the synthesis of circuits for succinct safety specifications given
in the AIG format. We show how AIG safety specifications can be decomposed
automatically into sub specifications. Then we propose symbolic compositional
algorithms to solve the synthesis problem compositionally starting for the
sub-specifications. We have evaluated the compositional algorithms on a set of
benchmarks including those proposed for the first synthesis competition
organised in 2014 by the Synthesis Workshop affiliated to the CAV conference.
We show that a large number of benchmarks can be decomposed automatically and
solved more efficiently with the compositional algorithms that we propose in
this paper.Comment: In Proceedings SYNT 2015, arXiv:1602.0078
Symblicit algorithms for optimal strategy synthesis in monotonic Markov decision processes
When treating Markov decision processes (MDPs) with large state spaces, using
explicit representations quickly becomes unfeasible. Lately, Wimmer et al. have
proposed a so-called symblicit algorithm for the synthesis of optimal
strategies in MDPs, in the quantitative setting of expected mean-payoff. This
algorithm, based on the strategy iteration algorithm of Howard and Veinott,
efficiently combines symbolic and explicit data structures, and uses binary
decision diagrams as symbolic representation. The aim of this paper is to show
that the new data structure of pseudo-antichains (an extension of antichains)
provides another interesting alternative, especially for the class of monotonic
MDPs. We design efficient pseudo-antichain based symblicit algorithms (with
open source implementations) for two quantitative settings: the expected
mean-payoff and the stochastic shortest path. For two practical applications
coming from automated planning and LTL synthesis, we report promising
experimental results w.r.t. both the run time and the memory consumption.Comment: In Proceedings SYNT 2014, arXiv:1407.493
Approximating Optimal Bounds in Prompt-LTL Realizability in Doubly-exponential Time
We consider the optimization variant of the realizability problem for Prompt
Linear Temporal Logic, an extension of Linear Temporal Logic (LTL) by the
prompt eventually operator whose scope is bounded by some parameter. In the
realizability optimization problem, one is interested in computing the minimal
such bound that allows to realize a given specification. It is known that this
problem is solvable in triply-exponential time, but not whether it can be done
in doubly-exponential time, i.e., whether it is just as hard as solving LTL
realizability.
We take a step towards resolving this problem by showing that the optimum can
be approximated within a factor of two in doubly-exponential time. Also, we
report on a proof-of-concept implementation of the algorithm based on bounded
LTL synthesis, which computes the smallest implementation of a given
specification. In our experiments, we observe a tradeoff between the size of
the implementation and the bound it realizes. We investigate this tradeoff in
the general case and prove upper bounds, which reduce the search space for the
algorithm, and matching lower bounds.Comment: In Proceedings GandALF 2016, arXiv:1609.0364
Mightyl: A compositional translation from mitl to timed automata
Metric Interval Temporal Logic (MITL) was first proposed in the early 1990s as a specification formalism for real-time systems. Apart from its appealing intuitive syntax, there are also theoretical evidences that make MITL a prime real-time counterpart of Linear Temporal Logic (LTL). Unfortunately, the tool support for MITL verification is still lacking to this day. In this paper, we propose a new construction from MITL to timed automata via very-weak one-clock alternating timed automata. Our construction subsumes the well-known construction from LTL to BĂĽchi automata by Gastin and Oddoux and yet has the additional benefits of being compositional and integrating easily with existing tools. We implement the construction in our new tool MightyL and report on experiments using Uppaal and LTSmin as back-ends
Hybrid Compositional Reasoning for Reactive Synthesis from Finite-Horizon Specifications
LTLf synthesis is the automated construction of a reactive system from a
high-level description, expressed in LTLf, of its finite-horizon behavior. So
far, the conversion of LTLf formulas to deterministic finite-state automata
(DFAs) has been identified as the primary bottleneck to the scalabity of
synthesis. Recent investigations have also shown that the size of the DFA state
space plays a critical role in synthesis as well.
Therefore, effective resolution of the bottleneck for synthesis requires the
conversion to be time and memory performant, and prevent state-space explosion.
Current conversion approaches, however, which are based either on
explicit-state representation or symbolic-state representation, fail to address
these necessities adequately at scale: Explicit-state approaches generate
minimal DFA but are slow due to expensive DFA minimization. Symbolic-state
representations can be succinct, but due to the lack of DFA minimization they
generate such large state spaces that even their symbolic representations
cannot compensate for the blow-up.
This work proposes a hybrid representation approach for the conversion. Our
approach utilizes both explicit and symbolic representations of the
state-space, and effectively leverages their complementary strengths. In doing
so, we offer an LTLf to DFA conversion technique that addresses all three
necessities, hence resolving the bottleneck. A comprehensive empirical
evaluation on conversion and synthesis benchmarks supports the merits of our
hybrid approach.Comment: Accepted by AAAI 2020. Tool Lisa for (a). LTLf to DFA conversion, and
(b). LTLf synthesis can be found here: https://github.com/vardigroup/lis
The Reactive Synthesis Competition: SYNTCOMP 2016 and Beyond
We report on the design of the third reactive synthesis competition (SYNTCOMP
2016), including a major extension of the competition to specifications in full
linear temporal logic. We give a brief overview of the synthesis problem as
considered in SYNTCOMP, and present the rules of the competition in 2016, as
well as the ideas behind our design choices. Furthermore, we evaluate the
recent changes to the competition based on the experiences with SYNTCOMP 2016.
Finally, we give an outlook on further changes and extensions of the
competition that are planned for the future.Comment: In Proceedings SYNT 2016, arXiv:1611.0717
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