We propose linear systems of hedge language equations (LSH) as a formalism to represent regular hedge languages. These linear systems are suitable for several computations in the algebra of regular hedge languages. We indicate algorithms to translate between representations by hedge automata and LSH, and for the computation of LSH for the intersection, quotient, left and right factors of regular hedge languages.

Queries on XML data are increasingly widespread in use and scope of application. However, optimization strategies are not yet as developed as they are for traditional DBMSs. Current strategies mostly involve logical or physical query plan optimization. We propose a novel optimization for XQuery using semantic information from the XML schema, where we rewrite a query into an equivalent query with fewer XPath expressions based on schema information. Our experimental results indicate that this optimization can result in substantial performance gains.

Conceptual modeling of XML data was made easier with the introduction of the XSEM model, which utilizes the MDA (Model-driven architecture) ideas of multi-level modeling. XCase is an implementation of this model, enabling users to model their problem domain as a Platform-independent model (PIM), from which Platform-specific models (PSM), XML schemas in our case, can be derived. The main advantage of this approach is maintainability of multiple XML schemas describing the same data from different views as XCase maintains connections between PIM and PSM levels, so that in case of a change to some element, this change can be propagated to all the places where this element is used.

An element algebra supporting the element calculus is proposed. The input and output of our algebra are xdm-elements. Formal definition of element algebra is offered. We consider algebraic expressions as mappings. A reduction of the element calculus to the element algebra is suggested.

The ability to specify, check and act upon constraints is vital to ensuring the overall quality of healthcare information. The Health Level 7 (HL7) Clinical Document Architecture (CDA), described through XML Schema, allows the specification of constraints through HL7 Templates, which can be implemented in Schematron. Schematron can be applied through Extensible Stylesheet Transformations (XSLT). This paper illustrates software and hardware solutions for constraint checking in the HL7 CDA. The two solutions are demonstrated in a Service Oriented Architecture (SOA) that includes both successful and failing XML Schema and Schematron constraint checks. The paper evaluates the application of constraints in the HL7 CDA and identifies some categories of constraints that require further investigation. The outcome of this evaluation shows that the ability to specify, check and act upon constraints through Schematron complements XML Schema processing. The two constraint approaches are very useful and practical, and should therefore be pursued further.

XML projection is one of the main adopted optimization techniques for reducing memory consumption in XQuery in-memory engines. The main idea behind this technique is quite simple: given a query Q over an XML document D, instead of evaluating Q on D, the query Q is evaluated on a smaller document D' obtained from D by pruning out, at loading-time, parts of D that are unrelevant for Q. The actual queried document D' is a projection of the original one, and is often much smaller than D due to the fact that queries tend to be quite selective in general. While projection techniques have been extensively investigated for XML querying, we are not aware of applications to XML updating. The purpose of the paper is to investigate a projection based optimization mechanism for updates.

In this paper, we propose an implementation and analyze the performances of checking XML key and functional dependency (XFD) satisfaction based on the definitions of XML key and XFD we proposed for the ordered XML model. It investigates how the number of occurrences of elements in the document and the number of paths in the constraints affect the behavior of XML key and XFD satisfaction checking. The results of the study show that both XML key and XFD can be checked in linear time with the number of tuples and with the number of paths involved in key and XFD. Also, XFD can be checked linearly with the number of XFDs.

The ever increasing number of adoptions from companies and the growing interest upon BPMN entails the need of having one more structured underlying conceptual model. There were different proposals to equip BPMN with a conceptual model, but the solution currently adopted remains unclear and too complex. Also the proposals submitted to the BPMN 2.0 RFP, which calls for a single notation to dene notation, metamodel and interchange format addressing BPDM concepts, are still unsatisfactory. We developed a new model starting from scratch, and the result of this work is a complete conceptual model for BPMN with a plain metamodel and its related XML-based serialization.