Revising Distributed UNITY Programs is NP-Complete

Bonakdarpour, Borzoo; Kulkarni, Sandeep S.

doi:10.21236/ada486602

Cited by 8 publications

(13 citation statements)

References 7 publications

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“…Finally, we model distribution by specifying read/write restrictions, whereas in controller synthesis, decentralized plants are modelled through partial observability [41,48]. As mentioned earlier, the issue of distribution drastically increases the complexity of synthesis [10,33]. This results is also known in the context of controller synthesis, but to the best of our knowledge, this paper introduces the first instance where synthesis of distributed fault-tolerant programs scales up and moderatesized programs beyond toy examples are successfully synthesized.…”

Section: Controller Synthesismentioning

confidence: 87%

“…We recall that the synthesis problem, if posed as a decision problem is known to be NP-complete in the size of state space [10,33] and our focus in this paper is to cope with this complexity for synthesizing witness solutions. Notice that constraint C3 obviously requires that the synthesized program has to be masking fault-tolerant.…”

Section: The Synthesis Problemmentioning

confidence: 99%

“…As mentioned in Sect. 4, the corresponding decision problem is known to be NP-complete [10,33] and our goal in this section is to develop an efficient symbolic (i.e., BDD-based) heuristic that can synthesize a rich class of programs. We validate this claim in Sects.…”

Section: The Symbolic Synthesis Algorithmmentioning

confidence: 99%

“…In other words, while determining recovery/safety-violating transitions, it is necessary to consider the interdependence between different transitions of distributed processes. This is the main reason that makes the decision problem of manipulating distributed programs to satisfy some safety or liveness properties is NP-complete in both absence and presence of faults [10,33]. To cope with this complexity, in our previous work, we developed heuristics for identifying recovery/safety-violating transitions (i.e., a witness solution to the decision problem) by considering the interdependence between different transitions of distributed processes [37].…”

Section: Introductionmentioning

confidence: 99%

“…Explicit-state techniques, however, are undesirable for the second part, as they suffer from the state explosion problem and prevent one from synthesizing programs with large state space. In other words, although the polynomial time complexity of the heuristics in [37] allows us to deal with the NP-complete problem of synthesizing distributed programs [10,33] to some extent, their explicit-state implementation is problematic with scaling up for larger programs.…”

Section: Introductionmentioning

confidence: 99%

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Symbolic synthesis of masking fault-tolerant distributed programs

2011

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We focus on automated addition of masking fault-tolerance to existing fault-intolerant distributed programs. Intuitively, a program is masking fault-tolerant, if it satisfies its safety and liveness specifications in the absence and presence of faults. Masking fault-tolerance is highly desirable in distributed programs, as the structure of such programs are fairly complex and they are often subject to various types of faults. However, the problem of synthesizing masking fault-tolerant distributed programs from their faultintolerant version is NP-complete in the size of the program's state space, setting the practicality of the synthesis problem in doubt. In this paper, we show that in spite of the high worst-case complexity, synthesizing moderate-sized masking distributed programs is feasible in practice. In particular, we present and implement a BDD-based synthesis heuristic for adding masking fault-tolerance to existing fault-intolerant distributed programs automatically. Our experiments validate the efficiency and effectiveness of our algorithm in the sense that synthesis is possible in reasonable amount of time and memory. We also identify several bottlenecks in synthesis of distributed programs depending upon the structure of

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Section: Controller Synthesismentioning

confidence: 87%

Section: The Synthesis Problemmentioning

confidence: 99%

Section: The Symbolic Synthesis Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Symbolic synthesis of masking fault-tolerant distributed programs

2011

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Incremental Realization of Safety Requirements: Non-determinism vs. Modularity

Ebnenasir

2015

Fundamentals of Software Engineering

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This paper investigates the impact of non-determinism and modularity on the complexity of incremental incorporation of safety requirements while preserving liveness (a.k.a. the problem of incremental synthesis). Previous work shows that realizing safety in non-deterministic programs under limited observability is an NP-complete problem (in the state space of the program), where limited observability imposes read restrictions on program components with respect to the local state of other components. In this paper, we present a surprising result that synthesizing safety remains an NP-complete problem even for deterministic programs! The results of this paper imply that non-determinism is not the source of the hardness of synthesizing safety in concurrent programs; instead, limited observability has a major impact on the complexity of realizing safety. We also provide a roadmap for future research on exploiting the benefits of modularization while keeping the complexity of incremental synthesis manageable.

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The complexity of automated addition of fault-tolerance without explicit legitimate states

et al. 2014

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Existing algorithms for automated model repair for adding fault-tolerance to fault-intolerant models incur an impediment that designers have to identify the set of legitimate states of the original model. This set determines states from where the original model meets its specification in the absence of faults. Experience suggests that of the inputs required for model repair, identifying such legitimate states is the most difficult. In this paper, we consider the problem of automated model repair for adding fault-tolerance where legitimate states are not explicitly given as input. We show that without this input, in some instances, the complexity of model repair increases substantially (from polynomial-time to NP-complete). In spite of this increase, we find that this formulation is relatively complete; i.e., if it was possible to perform model repair with explicit legitimate states, then it is also possible to do so without the explicit identification of the legitimate states. Finally, we show that if the problem of model repair can be solved with explicit legitimate states,

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Revising Distributed UNITY Programs is NP-Complete

Cited by 8 publications

References 7 publications

Symbolic synthesis of masking fault-tolerant distributed programs

Symbolic synthesis of masking fault-tolerant distributed programs

Incremental Realization of Safety Requirements: Non-determinism vs. Modularity

The complexity of automated addition of fault-tolerance without explicit legitimate states

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