Paper Review Form

Section I. Overview

A. Reader Interest

1. Which category describes this manuscript?

_x_Practice/Application/Case Study/Experience Report

___Research/Technology

___Survey/Tutorial/How-To

B. Content

1. Please explain how this manuscript advances this field of research and/or contributes something new to the literature.

This paper, we proposed an indexing scheme to enable RDF and RDF Schema to achieve efficient query retrievals on path expressions.

1. Is the manuscript technically sound?

___Yes

___Appears to be - but didn't check completely

_x_Partially

___No

C. Presentation

1. Are the title, abstract, and keywords appropriate?

_x_Yes

___No

1. Does the manuscript contain sufficient and appropriate references?

___References are sufficient and appropriate

_x_Important references are missing; more references are needed

___Number of references are excessive

2. Does the introduction state the objectives of the manuscript in terms that encourage the reader to read on?

___Yes

_x_Could be improved

___No

4. How would you rate the organization of the manuscript? Is it focused? Is the length appropriate for the topic?

___Satisfactory

_x_Could be improved

___Poor

5. Please rate and comment on the readability of this manuscript.

___Easy to read

_x_Readable - but requires some effort to understand

___Difficult to read and understand

___Unreadable

Section II. Evaluation

Please rate the manuscript. Explain your choice.

___Award Quality

___Excellent

___Good

_x_Fair

___Poor

Section III. Detailed Comments

This paper, we proposed an indexing scheme to enable RDF and RDF Schema to achieve efficient query retrievals on path expressions. It shows four types of partial graphs that can be obtained from RDF and RDF Schema. In addition, it shows suffix arrays on DAGs. by applying this scheme to path expressions extracted from the above graphs, we achieve efficient RDF query processing.

The previous approaches is used for XML data. However, in this paper they are applying it to RDF and RDF schema. Since XML data is a tree structure, enumeration of all possible path expressions in XML is an easy task. However, path expression cannot be as straightforward with RDF and RDF Schema, because they may contain multiple paths and/or cycles. For this reason, they limit their first targets to cases where RDF and RDF Schema do not contain cycles.

In the paper they say; they limit their target to DAGs. But they claim that their scheme can be applicable to many applications due to the fact that a large majority of RDF data in real applications is expressible as DAGs. And they give the WordNet , a famous on-line lexical database written in RDF, as an example, that does not contain cycles. Yet, they should have coped with cycles. then introduce a method to cope with cycles in the paper.

In the paper they briefly explain a previous work (Yamamoto et al.), then they pointed out some shortcomings, then propose a method.