CTL model checking for processing simple XPath queries

Question

1. What have the authors contributed in "Ctl model checking for processing simple xpath queries" ?

2. What have the authors stated for future works in "Ctl model checking for processing simple xpath queries" ?

3. How can the authors add past operators to CTL language?

4. What is the real bottleneck of XMChecker?

Accepted Answer

The authors investigate the potential of a technique based on Computation Tree Logic ( CTL ) model checking for evaluating queries expressed in ( a subset of ) XPath.. The authors report on experiments based on the model checker NuSMV, and compare their results with alternative academic XPath processors.. The authors comment on the advantages and drawbacks of the application of their model checking-based approach to XPath processing.

Accepted Answer

The authors see many directions for future work, but list only some of them.. Their goal is to study a systematic way to avoid processing XML regions that are irrelevant for the query, and to integrate it with XML compression.. This may be because it is tuned to a very different input format.. Since model checkers are designed to work on cyclic structures, this seems a good area in which a model checking-based approach has potential.

Accepted Answer

By adding past operators to CTL language, that is, the backward looking analogues of EX and EF, it is possible to capture all relative forward XPath queries.

Accepted Answer

XMChecker’s real bottleneck is the long compilation time, i.e., the time taken by NuSMV to encode the high-level description of the XML document into a low-level OBDD-based one.

Accepted Answer

Tree pattern queries, similar to the ones the authors use in this paper, have already been investigated in [6], where the authors propose query minimization algorithms, in [11], where the authors devise algorithms to aggregate an input set of queries into a smaller set such that a given space constraint is met and the loss of precision is minimal, and in [20], where the authors study the corresponding containment and equivalence problems.

Accepted Answer

The authors measured the CPU times (in seconds) needed to execute the following tasks: model checking (“query evaluation”), and converting the model into NuSMV’s internal, symbolic representation.

Accepted Answer

A different algorithm here could have a double positive effect: reducing the model compilation time, and — as the models get smaller — reducing the query evaluation times.

Accepted Answer

In [16] the authors propose an algorithm that embeds a Core XPath query into an algebraic expression over sets of nodes of the tree representing an XML document, and then evaluates the algebraic expression in order to process the query.

Accepted Answer

Then,1. the absolute query /[p] is successful if, and only if, T, r |=CTL ω(p); 2. the answer set of the relative query //[p] with respect to T equals the truth set of the CTL formula ω(p) with respect to T .

Accepted Answer

If the authors only consider the pure model checking time, XMChecker works very well: in several cases its performance is in the same league as that of MacMill, one of the fastest XPath processors currently available.

Accepted Answer

It is able to represent missing or duplicated data as well as nested information [1], and, hence, provides a suitable data model for semistructured data.

Accepted Answer

The relation between model checking and query processing for semistructured data goes back at least to [3], where it was formulated in terms of suitable modal-like logics.

Accepted Answer

Their main contributions are the following:1. The authors devise a linear translation of the query evaluation problem for Simple XPath into the model checking problem for CTL.

CTL model checking for processing simple XPath queries

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Most frequently asked questions

1. What have the authors contributed in "Ctl model checking for processing simple xpath queries" ?

2. What have the authors stated for future works in "Ctl model checking for processing simple xpath queries" ?

3. How can the authors add past operators to CTL language?

4. What is the real bottleneck of XMChecker?

5. What are the advantages of using a tree pattern query?

6. How many times did the authors need to perform the following tasks?

7. What could be the effect of a different algorithm?

8. What is the idea behind the Core XPath algorithm?

9. what is the answer set of the relative query /[p] with respect to a?

10. What is the way to evaluate XMChecker?

11. What is the way to represent data on the Web?

12. What is the relation between model checking and query processing for semistructured data?

13. What is the main contribution of the paper?

Figures

Citations

Mediation on XQuery Views

The First Twente Data Management Workshop (TDM'04) on XML Databases and Information Retrieval. Proceedings

A logic-based approach to cache answerability for XPath queries

First order Büchi automata and their application to verification of LTL specifications

Combining temporal logics for querying XML documents

References

Automatic verification of finite-state concurrent systems using temporal logic specifications

Symbolic Model Checking

Symbolic model checking: 10/sup 20/ states and beyond

NuSMV 2: An OpenSource Tool for Symbolic Model Checking

Data on the Web: From Relations to Semistructured Data and XML

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