Using variable automata for querying data graphs

Vrgoč, Domagoj

doi:10.1016/j.ipl.2014.10.019

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…For the sake of completeness, we also include results on another model of automata for data words called variable automata, or VFA for short, where variables are used to store data values. Originally introduced in [12] to reason about languages over infinite alphabets, they can easily be extended to operate over data words [29]. They define a class of languages orthogonal to the ones captured by formalisms in this paper.…”

Section: Discussionmentioning

confidence: 99%

Regular expressions for data words

Libkin

Tan

Vrgoč³

2015

Journal of Computer and System Sciences

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Section: Discussionmentioning

confidence: 99%

Regular expressions for data words

Libkin

Tan

Vrgoč³

2015

Journal of Computer and System Sciences

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“…In [10] variable automata were extended to consume data words, in order to express security policies (safety properties) for model checking programs that dynamically generate and operate over resources. Very recently, variable automata have been also used for querying graph databases [43]. In a similar approach, a variable LTL was has been investigated in [23].…”

Section: Introductionmentioning

confidence: 99%

Weighted Recognizability over Infinite Alphabets

Pittou¹,

Rahonis²

2017

Acta Cybern

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We introduce weighted variable automata over infinite alphabets and commutative semirings. We prove that the class of their behaviors is closed under sum, and under scalar, Hadamard, Cauchy, and shuffle products, as well as star operation. Furthermore, we consider rational series over infinite alphabets and we state a Kleene-Schützenberger theorem. We introduce a weighted monadic second order logic and a weighted linear dynamic logic over infinite alphabets and investigate their relation to weighted variable automata. An application of our theory, to series over the Boolean semiring, concludes to new results for the class of languages accepted by variable automata.

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“…One way to design querying languages for data graphs is to extend RPQs using frameworks that handle words on infinite alphabets [16,15,12,23]. Expressiveness and efficient algorithms for query evaluation are conflicting goals for designing such languages.…”

Section: Introductionmentioning

confidence: 99%

Nesting Depth of Operators in Graph Database Queries: Expressiveness Vs. Evaluation Complexity

Praveen,

Srivathsan

2016

Preprint

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Designing query languages for graph structured data is an active field of research, where expressiveness and efficient algorithms for query evaluation are conflicting goals. To better handle dynamically changing data, recent work has been done on designing query languages that can compare values stored in the graph database, without hard coding the values in the query. The main idea is to allow variables in the query and bind the variables to values when evaluating the query. For query languages that bind variables only once, query evaluation is usually NP-complete. There are query languages that allow binding inside the scope of Kleene star operators, which can themselves be in the scope of bindings and so on. Uncontrolled nesting of binding and iteration within one another results in query evaluation being Pspace-complete.We define a way to syntactically control the nesting depth of iterated bindings, and study how this affects expressiveness and efficiency of query evaluation. The result is an infinite, syntactically defined hierarchy of expressions. We prove that the corresponding language hierarchy is strict. Given an expression in the hierarchy, we prove that it is undecidable to check if there is a language equivalent expression at lower levels. We prove that evaluating a query based on an expression at level i can be done in Σi in the polynomial time hierarchy. Satisfiability of quantified Boolean formulas can be reduced to query evaluation; we study the relationship between alternations in Boolean quantifiers and the depth of nesting of iterated bindings.

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Using variable automata for querying data graphs

Cited by 3 publications

References 9 publications

Regular expressions for data words

Regular expressions for data words

Weighted Recognizability over Infinite Alphabets

Nesting Depth of Operators in Graph Database Queries: Expressiveness Vs. Evaluation Complexity

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