Results 1  10
of
10
Efficient Static Analysis of XML Paths and Types
, 2008
"... We present an algorithm to solve XPath decision problems under regular tree type constraints and show its use to statically typecheck XPath queries. To this end, we prove the decidability of a logic with converse for finite ordered trees whose time complexity is a simple exponential of the size of ..."
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Cited by 60 (33 self)
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We present an algorithm to solve XPath decision problems under regular tree type constraints and show its use to statically typecheck XPath queries. To this end, we prove the decidability of a logic with converse for finite ordered trees whose time complexity is a simple exponential of the size of a formula. The logic corresponds to the alternation free modal µcalculus without greatest fixpoint, restricted to finite trees, and where formulas are cyclefree. Our proof method is based on two auxiliary results. First, XML regular tree types and XPath expressions have a linear translation to cyclefree formulas. Second, the least and greatest fixpoints are equivalent for finite trees, hence the logic is closed under negation. Building on these results, we describe a practical, effective system for solving the satisfiability of a formula. The system has been experimented with some decision problems such as XPath emptiness, containment, overlap, and coverage, with or without type constraints. The benefit of the approach is that our system can be effectively used in static analyzers for programming languages
Exploiting schemas in data synchronization
, 2007
"... Increased reliance on optimistic data replication has led to burgeoning interest in tools and frameworks for synchronizing disconnected updates to replicated data. But good data synchronizers are challenging both to specify and to build. We have implemented a generic synchronization framework, calle ..."
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Cited by 23 (13 self)
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Increased reliance on optimistic data replication has led to burgeoning interest in tools and frameworks for synchronizing disconnected updates to replicated data. But good data synchronizers are challenging both to specify and to build. We have implemented a generic synchronization framework, called Harmony, that can be used to build statebased synchronizers for a wide variety of treestructured data formats. A novel feature of this framework is that the synchronization process—in particular, the recognition of conflicts—is driven by the schema of the structures being synchronized. We formalize Harmony’s synchronization algorithm, prove that it obeys a simple and intuitive specification, and illustrate, using simple address books as a case study, how it can be used to synchronize trees representing a variety of specific forms of application data, including sets, records, tuples, and relations.
Expressiveness and complexity of graph logic
, 2007
"... We investigate the complexity and expressive power of a spatial logic for reasoning about graphs. This logic was previously introduced by Cardelli, Gardner, and Ghelli, and provides the simplest setting in which to explore such results for spatial logics. We study several forms of the logic: the log ..."
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Cited by 15 (1 self)
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We investigate the complexity and expressive power of a spatial logic for reasoning about graphs. This logic was previously introduced by Cardelli, Gardner, and Ghelli, and provides the simplest setting in which to explore such results for spatial logics. We study several forms of the logic: the logic with and without recursion, and with either an exponential or a linear version of the basic composition operator. We study the combined complexity and the expressive power of the four combinations. We prove that, without recursion, the linear and exponential versions of the logic correspond to significant fragments of firstorder (FO) and monadic secondorder (MSO) logics; the two versions are actually equivalent to FO and MSO on graphs representing strings. However, when the two versions are enriched withstyle recursion, their expressive power is sharply increased. Both are able to express PSPACEcomplete problems, although their combined complexity and data complexity still belong to PSPACE.
From separation logic to firstorder logic
 In FoSSaCs’05
, 2005
"... Abstract. Separation logic is a spatial logic for reasoning locally about heap structures. A decidable fragment of its assertion language was presented in [3], based on a bounded model property. We exploit this property to give an encoding of this fragment into a firstorder logic containing only th ..."
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Cited by 14 (0 self)
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Abstract. Separation logic is a spatial logic for reasoning locally about heap structures. A decidable fragment of its assertion language was presented in [3], based on a bounded model property. We exploit this property to give an encoding of this fragment into a firstorder logic containing only the propositional connectives, quantification over the natural numbers and equality. This result is the first translation from Separation Logic into a logic which does not depend on the heap, and provides a direct decision procedure based on wellstudied algorithms for firstorder logic. Moreover, our translation is compositional in the structure of formulae, whilst previous results involved enumerating either heaps or formulae arising from the bounded model property. 1
Expressiveness of a spatial logic for trees
 In LICS 2005
, 2005
"... In this paper we investigate the quantifierfree fragment of the TQL logic proposed by Cardelli and Ghelli. The TQL logic, inspired from the ambient logic, is the core of a query language for semistructured data represented as unranked and unordered trees. The fragment we consider here, named STL, c ..."
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Cited by 13 (2 self)
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In this paper we investigate the quantifierfree fragment of the TQL logic proposed by Cardelli and Ghelli. The TQL logic, inspired from the ambient logic, is the core of a query language for semistructured data represented as unranked and unordered trees. The fragment we consider here, named STL, contains as main features spatial composition and location as well as a fixed point construct. We prove that satisfiability for STL is undecidable. We show also that STL is strictly more expressive than the Presburger monadic secondorder logic (PMSO) of Seidl, Schwentick and Muscholl when interpreted over unranked and unordered edgelabelled trees. We define a class of tree automata whose transitions are conditioned by arithmetical constraints; we show then how to compute from a closed STL formula a tree automaton accepting precisely the models of the formula. Finally, still using our tree automata framework, we exhibit some syntactic restrictions over STL formulae that allow us to capture precisely the logics MSO and PMSO. 1
An extensional spatial logic for mobile processes
 In Proc. of CONCUR, volume 3170 of LNCS
, 2004
"... Abstract. Existing spatial logics for concurrency are intensional, in the sense that they induce an equivalence that coincides with structural congruence. In this work, we study a contextual spatial logic for the πcalculus, which lacks the spatial operators to observe emptyness, parallel composition ..."
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Cited by 9 (0 self)
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Abstract. Existing spatial logics for concurrency are intensional, in the sense that they induce an equivalence that coincides with structural congruence. In this work, we study a contextual spatial logic for the πcalculus, which lacks the spatial operators to observe emptyness, parallel composition and restriction, and only has composition adjunct and hiding. We show that the induced logical equivalence coincides with strong early bisimilarity. The proof of completeness involves the definition of nontrivial formulas, including characteristic formulas for restrictionfree processes up to bisimilarity. This result allows us to isolate the extensional core of spatial logics, decomposing spatial logics into a part that counts (given by the intensional operators) and a part that observes (given by their adjuncts). We also study how enriching the core extensional spatial logic with intensional operators affects its separative power. 1
Bigraphical Logics for XML
, 2005
"... Bigraphs are emerging as an interesting model that can represent both the picalculus and the ambient calculus. Bigraphs are built orthogonally on two structures: a hierarchical `place' graph for locations and a `link' (hyper)graph for connections. ..."
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Cited by 7 (2 self)
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Bigraphs are emerging as an interesting model that can represent both the picalculus and the ambient calculus. Bigraphs are built orthogonally on two structures: a hierarchical `place' graph for locations and a `link' (hyper)graph for connections.
BiLog: Spatial Logics for Bigraphs
, 2005
"... Bigraphs are emerging as a (meta)model for concurrent calculi, like CCS, ambients, πcalculus, and Petri nets. They are built orthogonally on two structures: a hierarchical place graph for locations and a link (hyper)graph for connections. Aiming at describing bigraphical structures, we introduce a ..."
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Cited by 1 (0 self)
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Bigraphs are emerging as a (meta)model for concurrent calculi, like CCS, ambients, πcalculus, and Petri nets. They are built orthogonally on two structures: a hierarchical place graph for locations and a link (hyper)graph for connections. Aiming at describing bigraphical structures, we introduce a general framework, BiLog, whose formulae describe arrows in monoidal categories. We then instantiate the framework to bigraphical structures and we obtain a logic that is a natural composition of a place graph logic and a link graph logic. We explore the concepts of separation and sharing in these logics and we prove that they generalise well known spatial logics for trees, graphs and tree contexts. As an application, we show how XML data with links and web services can be modelled by bigraphs and described by BiLog. The framework can be extended by introducing dynamics in the model and a standard temporal modality in the logic. However, in some cases, temporal modalities can be already expressed in the static framework. To testify this, we show how to encode a minimal spatial logic for CCS in an instance of BiLog.
Migration et Mobilite: Semantique et Applications
 Activity Report
, 2003
"... 2003 Activity Report of Project MIMOSA ..."
von
"... This thesis investigates a pragmatic approach to typing, static analysis and static optimization of Web query languages, in special the Web query language Xcerpt[43]. The approach is pragmatic in the sense, that no restriction on the types are made for decidability or efficiency reasons, instead pre ..."
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This thesis investigates a pragmatic approach to typing, static analysis and static optimization of Web query languages, in special the Web query language Xcerpt[43]. The approach is pragmatic in the sense, that no restriction on the types are made for decidability or efficiency reasons, instead precision is given up if necessary. Pragmatics on the dynamic side means to use types not only to ensure validity of objects operating on, but also influencing query selection based on types. A typing language for typing of graph structured data on the Web is introduced. The Graphs in mind are based on spanning trees with references, the typing languages is based on regular tree grammars [37, 38] with typed reference extensions. Beside ordered data in the spirit of XML, unordered data (i.e. in the spirit of the Xcerpt data model or RDF) can be modelled using regular expressions under unordered interpretation – this approach is new. An operational semantics for ordered and unordered types is given based on specialized regular tree automata[21] and counting constraints[67] (them again based on Presburger arithmetic formulae). Static type checking of Xcerpt query and construct terms is introduced, as well as optimization of Xcerpt query terms based on schema information.