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Yoad Lustig

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3 papers

2 author rows

CSL Conference 2011 Conference Paper

Synthesis from Probabilistic Components

Yoad Lustig
Sumit Nain
Moshe Y. Vardi

Synthesis is the automatic construction of a system from its specification. In classical synthesis algorithms, it is always assumed that the system is "constructed from scratch" rather than composed from reusable components. This, of course, rarely happens in real life, where almost every non-trivial commercial software system relies heavily on using libraries of reusable components. Furthermore, other contexts, such as web-service orchestration, can be modeled as synthesis of a system from a library of components. Recently, Lustig and Vardi introduced dataflow and control-flow synthesis from libraries of reusable components. They proved that dataflow synthesis is undecidable, while control-flow synthesis is decidable. In this work, we consider the problem of control-flow synthesis from libraries of probabilistic components. We show that this more general problem is also decidable.

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GandALF Workshop 2011 Workshop Paper

Synthesis from Recursive-Components Libraries

Yoad Lustig
Moshe Vardi

Synthesis is the automatic construction of a system from its specification. In classical synthesis algorithms it is always assumed that the system is "constructed from scratch" rather than composed from reusable components. This, of course, rarely happens in real life. In real life, almost every non-trivial commercial software system relies heavily on using libraries of reusable components. Furthermore, other contexts, such as web-service orchestration, can be modeled as synthesis of a system from a library of components. In 2009 we introduced LTL synthesis from libraries of reusable components. Here, we extend the work and study synthesis from component libraries with ``call and return'' control flow structure. Such control-flow structure is very common in software systems. We define the problem of Nested-Words Temporal Logic (NWTL) synthesis from recursive component libraries, where NWTL is a specification formalism, richer than LTL, that is suitable for ``call and return'' computations. We solve the problem, providing a synthesis algorithm, and show the problem is 2EXPTIME-complete, as standard synthesis.

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LPAR Conference 2006 Conference Paper

On Locally Checkable Properties

Orna Kupferman
Yoad Lustig
Moshe Y. Vardi

Abstract The large computational price of formal verification of general ω -regular properties has led to the study of restricted classes of properties, and to the development of verification methodologies for them. Examples that have been widely accepted by the industry include the verification of safety properties, and bounded model checking. We introduce and study another restricted class of properties – the class of locally checkable properties. For an integer k ≥1, a language L ⊆ Σ ω is k-checkable if there is a language R ⊆ Σ k (of “allowed subwords”) such that a word w belongs to L iff all the subwords of w of length k belong to R. A property is locally checkable if its language is k -checkable for some k. Locally checkable properties, which are a special case of safety properties, are common in the specification of systems. In particular, one can often bound an eventuality constraint in a property by a fixed time frame. The practical importance of locally checkable properties lies in the low memory demand for their run-time verification. A monitor for a k -checkable property needs only a record of the last k computation cycles. Furthermore, even if a large number of k -checkable properties are monitored, the monitors can share their memory, resulting in memory demand that do not depend on the number of properties monitored. This advantage of locally checkable properties makes them particularly suitable for run-time verification. In the paper, we define locally checkable languages, study their relation to other restricted classes of properties, study the question of deciding whether a property is locally checkable, and study the relation between the size of the property (specified by an LTL formula or an automaton) and the smallest k for which the property is k -checkable.

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