Structural Properties of XPath Fragments

Benedikt, Michael; Fan, Wenfei; Kuper, Gabriel M.

doi:10.1007/3-540-36285-1_6

Cited by 57 publications

(53 citation statements)

References 15 publications

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“…As e is downward, we can use the semantics of + in a straightforward manner to conclude that id C ⊆ e C if and only if id C ⊆ e ′′ C and id C ∩ e C = ∅ otherwise. 2. e = e 1 • e 2 .…”

Section: Results Using Direction and Localitymentioning

confidence: 99%

“…Benedikt et al [2] studied the expressive power of the XPath fragments with and without the parent axis, with and without ancestor and descendant axes, and with and without qualifiers (which are π 1 -conditions). Furthermore, they studied closure properties of these XPath fragments under intersection and complement.…”

Section: Related Workmentioning

confidence: 99%

“…Notice in particular that the separation results on graphs of Fletcher et al do not necessarily also apply to trees. In addition, the expressiveness results for several XPath fragments [2,12,19,20,24,25,27] in the context of XML do not provide a complete picture of the relative expressive power of the navigational query languages we consider here. As a first step towards a complete picture of the relative expressive power, we study the expressive power of downward fragments: these are navigational query languages that only allow downward navigation in the tree via parent-child relations.…”

Section: Introductionmentioning

confidence: 97%

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Comparing the expressiveness of downward fragments of the relation algebra with transitive closure on trees

Hellings

Gyssens

et al. 2020

Information Systems

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Motivated by the continuing interest in the tree data model, we study the expressive power of downward navigational query languages on trees and chains. Basic navigational queries are built from the identity relation and edge relations using composition and union. We study the effects on relative expressiveness when we add transitive closure, projections, coprojections, intersection, and difference; this for boolean queries and path queries on labeled and unlabeled structures. In all cases, we present the complete Hasse diagram. In particular, we establish, for each query language fragment that we study on trees, whether it is closed under difference and intersection. * This is a revised and extended version of the conference paper 'Relative Expressive Power of Downward Fragments of Navigational Query Languages on Trees and Chains', presented at the 15th International Symposium on Database Programming Languages, Pittsburgh, Pennsylvania, United States (DBPL 2015). Yuqing Wu carried out part of her work during a sabbatical visit to Hasselt University with a Senior Visiting Postdoctoral Fellowship of the Research Foundation Flanders (FWO).

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Section: Results Using Direction and Localitymentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Comparing the expressiveness of downward fragments of the relation algebra with transitive closure on trees

Hellings

Gyssens

et al. 2020

Information Systems

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“…Our formalisation captures no more than the expressive power of CSS3 selectors, which helps us obtain the much lower complexity NP and enables the use of highly-optimised SMT-solvers. There is a plethora of other work on logics and automata on unranked trees (with and without data), e.g., see [42,6,27,69,70,68,43,33,5,50,23,40,24,21,59,17,26] and the surveys [39,49,9]. However, none of these formalisms can capture certain aspects of CSS selectors (e.g.…”

Section: Evaluations Of Optimisationsmentioning

confidence: 99%

CSS Minification via Constraint Solving

Hague

Lin

Hong

2019

ACM Trans. Program. Lang. Syst.

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Minification is a widely-accepted technique which aims at reducing the size of the code transmitted over the web. This paper concerns the problem of semantic-preserving minification of Cascading Style Sheets (CSS) -the de facto language for styling web documents -based on merging similar rules.The cascading nature of CSS makes the semantics of CSS files sensitive to the ordering of rules in the file. To automatically identify rule-merging opportunities that best minimise file size, we reduce the rule-merging problem to a problem concerning "CSS-graphs", i.e., node-weighted bipartite graphs with a dependency ordering on the edges, where weights capture the number of characters.Constraint solving plays a key role in our approach. Transforming a CSS file into a CSS-graph problem requires us to extract the dependency ordering on the edges (an NP-hard problem), which requires us to solve the selector intersection problem. To this end, we provide the first full formalisation of CSS3 selectors (the most stable version of CSS) and reduce their selector intersection problem to satisfiability of quantifier-free integer linear arithmetic, for which highly-optimised SMT-solvers are available. To solve the above NP-hard graph optimisation problem, we show how Max-SAT solvers can be effectively employed. We have implemented our rule-merging algorithm, and tested it against approximately 70 real-world examples (including examples from each of the top 20 most popular websites). We also used our benchmarks to compare our tool against six well-known minifiers (which implement other optimisations). Our experiments suggest that our tool produced larger savings. A substantially better minification rate was shown when our tool is used together with these minifiers.

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“…Queries can become more complicated, and a series of interdependent queries may be used for more advanced checks, for example to identify inconsistent use of semantic attributes. Our analysis tool Goanna uses such treepattern matching [BFK02] on the AST. However, pattern matching is fundamentally limiting, since it only searches for keywords and their context, but is unable to take control flow, data flow, or other semantic information into account.…”

Section: Static Analysis Technologiesmentioning

confidence: 99%

Report on the third static analysis tool exposition (SATE 2010)

Okun¹,

Delaitre²,

Black³

2011

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Abstract:The NIST Software Assurance Metrics And Tool Evaluation (SAMATE) project conducted the third Static Analysis Tool Exposition (SATE) in 2010 to advance research in static analysis tools that find security defects in source code. The main goals of SATE were to enable empirical research based on large test sets, encourage improvements to tools, and promote broader and more rapid adoption of tools by objectively demonstrating their use on production software.Briefly, participating tool makers ran their tool on a set of programs. Researchers led by NIST performed a partial analysis of tool reports. The results and experiences were reported at the SATE 2010 Workshop in Gaithersburg, MD, in October, 2010. The tool reports and analysis were made publicly available in 2011.This special publication consists of the following three papers. "The Third Static Analysis Tool Exposition (SATE 2010)," by Vadim Okun, Aurelien Delaitre, and Paul E. Black, describes the SATE procedure and provides observations based on the data collected. The other two papers are written by participating tool makers."Goanna Static Analysis at the NIST Static Analysis Tool Exposition," by Mark Bradley, Ansgar Fehnker, Ralf Huuck, and Paul Steckler, introduces Goanna, which uses a combination of static analysis with model checking, and describes its SATE experience, tool results, and some of the lessons learned in the process. Serguei A. Mokhov introduces a machine learning approach to static analysis and presents MARFCAT's SATE 2010 results in "The use of machine learning with signaland NLP processing of source code to fingerprint, detect, and classify vulnerabilities and weaknesses with MARFCAT." Keywords:Software security; static analysis tools; security weaknesses; vulnerability Certain instruments, software, materials, and organizations are identified in this paper to specify the exposition adequately. Such identification is not intended to imply recommendation or endorsement by NIST, nor is it intended to imply that the instruments, software, or materials are necessarily the best available for the purpose.NIST SP 500-283 2 This paper describes the SATE procedure and provides our observations based on the data collected. We improved the procedure based on lessons learned from our experience with previous SATEs. One improvement was selecting programs based on entries in the Common Vulnerabilities and Exposures (CVE) dataset. Other improvements were selection of tool warnings that identify the CVE entries, expanding the C track to a C/C++ track, having largerup to 4 million lines of code -test cases, clarifying further the analysis categories, and having much more detailed analysis criteria.This paper identifies several ways in which the released data and analysis are useful. First, the output from running many tools on production software can be used for empirical research. Second, the analysis of tool reports indicates actual weaknesses that exist in the software and that are reported by the tools.Third, the CVE-selected test cases conta...

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Structural Properties of XPath Fragments

Cited by 57 publications

References 15 publications

Comparing the expressiveness of downward fragments of the relation algebra with transitive closure on trees

Comparing the expressiveness of downward fragments of the relation algebra with transitive closure on trees

CSS Minification via Constraint Solving

Report on the third static analysis tool exposition (SATE 2010)

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