Local XML functional dependencies

Liu, Jixue; Vincent, Millist W.; Liu, Chengfei

doi:10.1145/956699.956705

Cited by 20 publications

(8 citation statements)

References 9 publications

(21 reference statements)

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“…Most of them are based on path [3,[6][7][8][9][10][11][12][13][14][15][16], but Hartmann et al [17,18] and Ping Yan and Teng Lv [19,20] use subtrees to define XFDs. For clarity, every paragraph begins with "XFDS in [i]" where "[i]" denote one or more references.…”

Section: Previous Work For Xfdsmentioning

confidence: 99%

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An overview of functional dependencies in XML

Chen

Liao

2010

2010 International Conference on Educational and Information Technology

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The concept of functional dependencies plays an important role in relational databases where it is used in integrity enforcement and database design. The corresponding concept, functional dependencies in XML ( XFDs), has been widely investigated over the past few years. Although some proposals have been made and most of them are based on path that is a crucial factor for the expressive power ofXFDs, there seems to be no consensus on how to specify them. In this paper, we survey the previous work in terms of the approaches they employ. Some related issues are discussed. In particular, we analyze the effects of null values and how to compare element nodes with complex type. We also discuss the logical implication and normalization for XML in brief. A set of requirements for a good XFDs definition are concluded.

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Section: Previous Work For Xfdsmentioning

confidence: 99%

“…XFDs in [9][10][11]]. An XML functional dependency in [9] is an expression of the form P --Q, where P and Q are two sets of primary paths in a XML document tree.…”

Section: A Xfds Based On Pathsmentioning

confidence: 99%

An overview of functional dependencies in XML

Chen

Liao

2010

2010 International Conference on Educational and Information Technology

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“…where ε denotes null string, e ∈ E c ∪ E s , and "|", ", ", " * " denote union, connection and Kleene closure; 5) R denotes the map from E c to the attribute set; for e ∈ E c , any F (e) not ε or R(e) not ∅; 6) r ∈ E c is another different element name,∀e ∈ E c , r is the only flag in E c which is not in the alphabet of F (e). …”

Section: Dtd and Xml Document Treementioning

confidence: 99%

“…In order to eliminate abnormal XFD, we use the method similar with the one in [2] and [6]. But both methods cannot solve the text problems and not consider relative functional dependency when creating a new element.…”

Section: Generating Xnf Algorithmmentioning

confidence: 99%

XML Functional Dependency and Schema Normalization

Zhao

Xin

Zhang

2009

2009 Ninth International Conference on Hybrid Intelligent Systems

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Normalization theory is necessary for designing a good XML document. A good document means that it has minimal redundancy. The research on XML functional dependency and normalization is still an open problem. This paper first presents a path language of XML model, then proposes a new kind of XML functional dependency (XFD) that has stronger expression ability to XML functional dependency that can result in redundancies. In this paper, the problems of XFD logical implication and XFD closure are studied and a group of the corresponding inference rules is proposed. Based on the XFD, a kind of XML normal form (XNF) and an algorithm converting into XNF are also proposed in this paper.

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“…[4] and [5] are equal when there is no null values. Liu et al [8] defines a local XFD, similar to the way that relative key is defined in Ref. [6], it describes data constraints on the XML fragments.…”

Section: Introductionmentioning

confidence: 99%

Functional dependencies and its axiom system in XML

Zhao

Wang

Hou

et al. 2007

Wuhan Univ. J. of Nat. Sci.

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According to the analysis of existing complicated functional dependencies constraint, we conclude the conditions of defining functional dependency in XML, and then we introduce the concept of the node value equality. A new path language and a new definition of functional dependencies in XML (XFD) are proposed. XFD includes the relative XFD and the absolute XFD, in which absolute key and relative key are the particular cases. We focus on the logical implication and the closure problems, and propose a group of inference rules. Finally, some proofs of the correctness and completeness are given. XFD is powerful on expressing functional dependencies in XML causing data redundancy, and has a complete axiom system. Functional dependencies play an important role in database, which is widely used in integrity constraints and the design of database. Also this kind of data constraint mechanism plays an important role in XML data management. Considering that the XML data constraints come from the application semantic, we hope to express these semantic constraints in XML schema, so that the database can avoid operations that will cause inconsistency.To present functional dependencies, relational database utilizes relational schema, while XML has its own schema, such as XML Data [1] , XML Schema [2] , and XML DTD [3] . The semantic described by these specifications is insufficient to express functional dependencies. Many researches try to apply functional dependencies on XML but there are still unsolved problems. We read a large number of XML documents and take the widely used XML DTD in practice as the schema for our example, as shown in the following.Some researchers are attempting to extend the concept of functional dependencies on XML. Based on the concept of tree tuple, Arenas et al [4] propose a definition of functional dependencies in XML (XFD), which treats DTD as a relational schema, paths on the DTD are the attributes of the schema. Vincent et al [5] proposes a XFD based on the concept of closest node, similar to the way that key is defined in Ref.[6], closest node is the node mapped from the left side and the right side of the XFD in the XML tree, whose path instance has the maximum common prefix. Vincent et al [7] point out that the definitions in Ref.[4] and [5] are equal when there is no null

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Local XML functional dependencies

Cited by 20 publications

References 9 publications

An overview of functional dependencies in XML

An overview of functional dependencies in XML

XML Functional Dependency and Schema Normalization

Functional dependencies and its axiom system in XML

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