A User Interface for Distributed Multimedia Database Querying with Mediator Supported Refinement *

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1 A User Interface for Distributed Multimedia Database Querying with Mediator Supported Refinement * Isabel F. Cruz, Kimberly M. James Department of Computer Science - ADVIS Research Group Worcester Polytechnic Institute 100 Institute Road, Worcester, MA {cruz, ABSTRACT The Delaunay MM system supports an interactive, customizable interface for querying multimedia distributed databases, like Digital Libraries. Through this interface, users select virtual document styles that cater the display of query results to their needs, while also offering transparent pre- and post-query refinement and nested querying. Delaunay MM s virtual documents preserve context by maintaining a single customizable interface for result viewing. The advanced transparent query features rely on mediation to provide adept access to information. In this paper, we present the framework for Delaunay MM, its architecture, the user interface, and results of the first usability study. 1. INTRODUCTION With an increase in the number of users daily, the World Wide Web has become an indispensable technology. With increasingly diverse user populations and available technologies, the value of reliable searching and information navigation mechanisms is becoming more significant. The average user spends between five and fifteen minutes searching on the web before finding his or her first piece of useful information, with expert users completing the task in less than five minutes [12]. The gap between expert and novice capabilities is staggering. To reduce the overall time for searching, in both the novice and expert population, search interfaces must combine powerful search and refinement capabilities with intelligible views as not to overwhelm the user. Delaunay MM presents users with a unique search interface, supporting both pre- and post-query refinement for novice and expert users, as well as user-specified layout of query results. These capabilities are coupled with a framework that supports multiple information repositories and media types (image, video, text, and audio). The primary application of this work has been with digital libraries, but the principles and interface methods can be extended to other disparate information repositories like the World Wide Web. There are three concepts that make our approach unique: 1. Pre- and user-defined virtual document templates for defining spatial layout To address the needs of different users and a variety of applications, the spatial layout of the multimedia objects on the virtual document pages are visually specified on a template, the virtual document template, containing space-holders for these objects. Users may either select a predefined template or design one to match their needs. 2. Pre- and post-query refinement Through interactive interfaces both expert and novice users are able to refine their queries easily. Experts may refine their queries based on the attributes of the information repository and novices may use the Search Assistant to narrow their queries to relevant information repositories for pre-query refinement. Both novice and expert users can use the Refinement Assistant to resubmit queries using a representative set of results for post-query refinement. * Research supported in part by the National Science Foundation under CAREER Award IRI and CISE Research Instrumentation Grant Project Site:

2 3. Nested query boxes for specifying browsable groupings In the generated virtual document, the traversal between the retrieved objects associated with the visual representations is determined by the semantics associated with nesting query boxes. The user can therefore specify what information to retrieve, as well as, how that information is linked together via a visual representation. The end result is an automatically generated, browsable virtual document of multimedia objects that has been customized to the exact specifications of the user. The flexibility provided by this framework effectively supports a multitude of users, as well as information repositories, thus providing a global interface for information retrieval. Query Formation Search Assistant Search Refinement Virtual Page Display Metadata Warehouse Query Mediator Refinement Manager Layout Manager Data Wrapper DL1 External Resources Figure 1: DelaunayMM Architecture Data Wrapper DL2 After developing an interface we then developed the supporting architecture. Figure 1 provides an overview of the Delaunay MM architecture for querying and presenting multimedia data retrieved from digital libraries. This new architecture builds on the visual querying and layout design methods previously developed [3, 4]. Users begin by submitting keywords for their query. They may also select a layout style for result display, information repositories for querying, and the type of media objects to return (image, text, audio, or video) at this point. These parameters are recorded and used by the Refinement and Layout Managers to support query refinement and provide virtual document layout, respectively. Before the query is submitted to the individual information repositories the keywords are submitted to a resident resource, the Metadata Warehouse. This data warehouse [23] contains the keyword structure, a tree-like structure depicting the relationship between keywords, of all available repositories. Querying the Metadata Warehouse prior to sending the query to the different resources allows users to refine their query based on the general content of the different repositories. After selecting the query's context, the user s keywords are sent via data wrappers to the various information repositories, via the Query Mediator. Results are returned to the Query Mediator and then passed to the Refinement Manager. Through the Refinement Manager, users may refine their queries by selecting a group of representative objects. Finally, the final result objects are passed to the Layout Manager, which creates the Virtual Page. The following sections describe the interface, interaction methods with the back-end components and future work for Delaunay MM. 2. THE DELAUNAY MM INTERFACE The Delaunay MM interface supports different user types through a simplistic interface. This interface supports two levels of interaction, for expert and average or novice users, with each offering suitable levels of refinement and customization for the intended user group. The following sections describe the interface in detail. 2.1 Query Specification Users enter their query keywords on the initial page, as shown in Figure 2. Inclusion and exclusion of words, similar to the Boolean, is available through a hierarchical layout. This layout prevents the incorrect use of Boolean operators, and eliminates the need for user understanding of Boolean construction. This method is not fully Boolean in its logic, but it attempts to address the gap between the user s mental model and expected results, and the results obtained through the traditional method of Boolean specification. From this initial page users may optionally select information repositories and page formats. The defaults provided allow users to specify their queries quickly and easily, while the options allow more advanced users the flexibility of querying on information repository specific attributes or creating tailored templates to support their needs. Users may also retrieve saved queries through this interface. If users select to "Use the Advanced Search and Layout Features", they may refine their query based on repository attributes and/or create their own virtual document template. For example, the Perseus digital library [2] provides access to ancient coin, vase and sculpture images and text. With this content in mind, users may refine their query based on material type, name, or period of the given objects. This type of refinement is necessary for users familiar with information repository content and that have welldefined goals. Users are also able to select media element attributes. For example, if a user desires only front views for images or a specific text style, these preferences can be noted here. Advanced users may select to define a new virtual template to support their specific needs. It is through this

3 interface that users may utilize the nested and visual query box functionality [4]. To define their own template, users begin by placing objects on the virtual page using a toolbox, which contains all the supported media objects. The Query Box tool element allows users to associate specific objects with a single query, or to nest queries inside one another. For example in a nested query an inner query box can be nested within an outer query box. The outer treats data associated with any inner box as a nested collection, and is equivalent to browsing a nested relational table. In this case, if queries are specified for each inner query box, when viewing answers, one is able to traverse the elements of the inner result set and then traverse another nested tuple, accessible via the outer box. 2.2 Query Context, Confidence and Refinement To increase the number of relevant results and decrease the query time, a resident resource, the Metadata Warehouse, is provided. The Metadata Warehouse maintains a keyword tree for all available information repositories. The relationships described by this tree are simply Boolean, as shown in Figure 3. In our model, we assume that each information repository maintains keywords for each of their objects and are able to construct a tree for these keywords. Users' keywords are sent to this warehouse to determine in what context (on what branches of the tree) their keywords exist. Using the appropriate tree branches a virtual tree is constructed to represent globally the contexts available from all information repositories. Using the Search Assistant, users may select the appropriate contexts for their query, as shown in Figure 4. In Figure 4, the keyword entered is "T-Rex", abbreviation for Tyrannosaurus Rex. With this approach, any information repository can be modeled approximately without requiring a global definition for the repositories. Furthermore, because we are only maintaining trees that describe the information repository, we can manipulate the trees as needed to create the virtual structure for the Search Assistant. KyWrd1 Root KyWrd2 Object2 Object3 Object1 Boolean Relationships Object3 = Root ^ KyWrd2 Object3 = Root ^ KyWrd1 Object1 & 2 = Root ^ KyWrd1 Object1,2,&3 = Root ^ = AND; = NOT Figure 3: Keyword Tree Relationships Another benefit of this resident resource is saved query time for the user and the application. By supporting this type of context based pre-query refinement, the system can narrow what information repositories are queried, based on the users' selections in hopes of yielding the best results. When keywords are not found in the warehouse, a message is presented to the user to confirm their query submission. The Search Assistant is only available when users have used the standard query features; it is assumed that advanced users performing complex queries have a high confidence for finding results. Delaunay MM also offers post-query refinement to users when the number of returned objects is greater than the number selected on the initial query page, as shown in Figure 5. Because users select the maximum number of return results the application more effectively offers refinement guidance to meet individual user s needs. The alternative approach of creating an internal mechanism for defining refinement rules does not offer the flexibility necessary to support all user types, thus this approach was abandoned. Users are shown the complete set of returned objects in the left frame of the window. The objects in this frame are not shown in full detail in order to optimize screen space. For example, images are displayed as thumbnails and text is abbreviated. The details of each object are displayed in the right frame, "Full" tab (displays "Full Image", "Full Text", etc., depending on object type), when an object is selected. The "Other Info" tab displays supporting information, such as the owning resource, the keywords and the referencing web page for the object. Users may select an object by using the "Select Object" button or through selecting individual checkboxes. Once objects are selected they are used as a representative set for query refinement, which is similar to a collective More like this construct. These objects may also be used to create the virtual document. This final option ensures that the final results displayed reflect the users expectations and needs. 2.3 Virtual Document Display The query results are displayed in the form of a virtual document. The user, from the initial query page, may define this layout or accept a predefined one. Each predefined template is modeled after a specific user group s needs. For example, the Student/Researcher template gives priority to explanatory text over images or other objects, while the Comparison template is used to show objects side-by-side to allow comparing. The virtual document displayed is dependent upon the type of media objects available and the user s selected style. Figure 6 shows the Student/Researcher format. One notable inclusion is the "Go To Web Page" button. Selecting this option opens a new browser to display the

4 original web page for a particular object, or groups of objects. For example, the images shown in Figures 5 and 6, both come from the Wyoming Dinosaur Center 1. The Center s page format is noticeably different from either of Delaunay MM s and in general their page would be reached only after finding the Wyoming Dinosaur Center page in a list of search results from a search engine, and then traversing the various links within the web site. Through Delaunay MM, users have access to a multitude of query results and do not lose context by moving back and forth between a result page with links and the actual web sites. The option to view the original web site is an important tool but it does not interfere with the users ability to view results and preserve context [5]. Users may also save their query results from the virtual page, by providing a name for the results and selecting the "Save Search Results" option. The saved searches are shown when the user returns to the Delaunay MM specification page. This option is especially useful to users who have used the application s refinement options. In the case of both pre- and post- query refinement, Delaunay MM generates queries for the individual information repositories that are not visible to the user. Given this transparent operation, providing a mechanism to save results is advantageous. 3. MEDIATOR SUPPORTED REFINEMENT As shown in Figure 1, Delaunay MM s information retrieval is supported by a complex interaction between the Query Mediator and external resources. This interaction is the crux of the application s ability to provide suitable results to users queries with mediation [17] being used to support this functionality. Both pre- and post-query refinement use similar mediation techniques, although their goals are different. Pre-query refinement focuses on providing users with the context of their keywords and allowing users to select from these available contexts to guide the query. On the other hand, post-query refinement uses a set of representative objects, as selected by the user, to rewrite a query, in order to return better results. In each case, a similar tree examining and merging process may be utilized to determine what information repositories should be consulted and keywords are sent to these repositories. The user s keywords are first sent to the Metadata Warehouse to determine their occurrence and placement in the available information repositories. If they are found here, the Metadata Warehouse passes the appropriate branches of the keyword tree to the Query Mediator. The Query Mediator then constructs a virtual 1 Images reprinted with the permission of the Wyoming Dinosaur Center: tree to present to the user via the Search Assistant. This virtual tree is an amalgamation of the branches supplied by the Metadata Warehouse. In the merging process, nodes are rearranged when necessary. The tree produced through this process is not erroneous, because we are only seeking to provide a general contextual structure to users and not a one-to-one mapping between all resources and the user s keywords. After the user has selected a context for his or her query, using the Search Assistant, the Query Mediator resolves these virtual contextual selections with the original keyword tree, for each information repository involved. Once the Query Mediator has selected which information repositories contain the appropriate context(s), a specific query for each is defined, again based on their individual keyword trees, and sent to the appropriate data wrappers. Once the results are received from the data wrappers, the Query Mediator then sends them to the Refinement Manager. If the number of returned objects is greater than the number selected by the user, the Refinement Manager displays all objects. After the user selects the objects to use for refinement, they are passed back to the Query Mediator with their individual keyword trees. Converse to the pre-query refinement, where trees are merged to find similarities, here trees are examined for their differences. The mediator uses these differences to dynamically create a new query. Another important difference in post-query refinement is the information repository selection criteria. Here, sources that may have been used previously may be excluded. For example, if the object set contains 75% of its object from resource1 and the remainder from resource3, previously used resource2 may now be excluded. The Query Mediator must also record previous queries to determine when an information repository should be reintroduced. The exact algorithm for exclusion/inclusion is a topic for future work. Similarly, defining when to broaden or narrow the scope of a query (e.g., when to use exclusion, i.e., "but not", versus inclusion, i.e., "or", terms) is another area for future work. The Query Mediator mediates to support both pre- and post- query refinement. It uses the information supplied by the Metadata Warehouse and the Refinement Manager, regarding the information repositories structures and objects, respectively, and its knowledge of previous searches to determine which information repositories are appropriate and the keywords necessary to return the best possible results. 4. USABILITY STUDY RESULTS In December 1998, 34 students participated in the first usability study of the current interface and architecture. This study focused on three components: the intuitiveness of the new interface, the applicability of the

5 approach to querying vast data resources, and defining the flaws in the approach and interface. We created a digital library, Digital Dinosaurs, for use with this study to provide a more engaging subject that would interest users of all types. The overall results of the study supported the approach and interface, noting minor changes that would significantly increase overall usability. For this study, users were asked to use Delaunay MM to submit two queries to various digital resources, and to create their own virtual page format using the original interface. Each query used different Delaunay MM attributes to tailor the interface to the specific task. Once finished, users were asked to complete a 40-question survey [18] in which they either affirmed or negated statements about each aspect of the interface. Two users were monitored to confirm that the study s usage scenarios and survey questions were fair. All other users performed the study over the course of a week for 30 to 45 minutes at their leisure. The results of this study led to many of the interface changes visible in Figures 2,4,5, and 6. Overall, the Query Specification and Refinement Assistant displays were ranked as being highly intuitive, with the Search Assistant and virtual page format displays being moderately intuitive. The Query Specification s keyword and attribute designation mechanisms were viewed as intuitive and useful, with more work necessary in defining the appropriate virtual document formats to support more users. Users agreed that the Search Assistant provided contextual information about the information sources and that they would prefer this prequery refinement to waiting longer for results. Overwhelming, users agreed that the Refinement Assistant interface allowed them to see the information needed to make an accurate selection (72%). Although the scenarios did not ask them to use the "Refine Search" option in the Refinement Assistant module, users found it to be an intuitive operation. Seventy-nine percent of users preferred viewing everything in one browser window, and only 24% preferred seeing a traditional list of URLs to the virtual page formats. Users also found the "Go to Web Page" option to be useful, and commented that because it was optional it added to the strength of interface. Finally, users found that creating their own page format, using the visual querying tools supplied, was unintuitive (57%) and thought it was more difficult than using the predefined formats (85%). Seventy-nine percent of users supplied extra comments about the interface and many users stated that Delaunay MM s approach was useful, and exceeded the capabilities of existing search engines and interfaces. Comments also discussed the need to expand the virtual page formats to support more user types. Based on the results and comments from users another format, hypertext, will be added. This format will present query results as a list of hypertext links with descriptions. The strength of this addition is that it allows expert users, searching for fast results, a familiar interface for retrieving information. The addition of this interface also makes hypertext results lists a subset of the available formats. Notably, only 41% of users thought an extension to allow non-text based querying (image, video or audio) would be beneficial, thus this extension is not actively being pursued. Although the overall results of the study were very positive, the user population was biased thus diminishing its capacity to prove global usability. With 59% of respondents being expert web searchers having high confidence in their searching capabilities, and all others being average, this study did not have an accurate sampling of "average" web users [12]. All respondents noted that they are typically successful in finding information on the Internet, with most (88%) finding the necessary information within submitting a few searches. This bias was most heavily noted in response to the statement: I would prefer this interface to existing search interfaces. Although there was a close split between positive and negative responses (36% and 40%, respectively) many of the users commented that the response time of our approach was too slow. This slow response time is a result of the need to transfer multimedia elements, as opposed to plain text html, over the Internet, and is an area for further technical exploration. Ultimately, for expert web searchers response time is a key usability factor, thus the interface was not regarded as highly by these individuals. [12] Although many users were pleased to see a new approach to information display and retrieval, there were some that found the uniqueness of the approach unsettling. One user stated, "My general idea on the whole thing is that people aren t used to it. Everybody expects to see textual links and descriptions when you give them pictures, audio/video, that scares them". This concern may be attributed to the high number of expert users who are successful with existing interfaces and reluctant to change. This concern also highlights the uniqueness in this approach, showing that many users have not been exposed previously to this type of query interface. 5. RELATED WORK Currently, numerous Digital Library projects are researching various mechanisms for retrieval of information, displaying results, information organization, and other digital library enhancement capabilities. Many of these projects deal with specific media forms or information types. While this specialized research is beneficial to the Digital Library discipline, the overriding requirement for a single interface to the wealth of multimedia information has been neglected.

6 5.1 Query Definition and Submission Defining the query can be one of the most difficult aspects of searching. Users are generally asked to present a series of keywords, with associated Boolean terms, to describe their subject interest. This definition can be difficult and improper assumptions about context and word choice can be easily made depending upon the query resolution method. To combat these difficulties, alternative query formats, such as natural language and preview queries, have been developed [14,15,19]. Given the scope of Delaunay MM, as a global interface, and the restrictions of other query definition formats, the standard use of keywords drives the application s query specification. To offer more flexibility in query creation, users may select to narrow their criterion based on the attributes of the selected information repositories. This option allows the level of query refinement offered in [14], but does not limit the overall interface to a single information type or repository. There are also many methods used to submit queries to databases, or other information repositories. Delaunay MM 's primary focus is on mediated querying for refinement. Similarly to [11], a query is first submitted to the resident resource to gain an understanding of the keywords' context and also to gauge what information repositories are most useful for the particular query. Unlike [11], this resource does not maintain a simple mapping of words with the number of information repositories that contain that word, thus mediation is used to direct the query to the appropriate resource. Similarly, when users select objects to use as representative objects for refinement the Query Mediator must possess "knowledge" about the previous query, or queries, and must rewrite the query based on this "knowledge". DISCO's approach to mediated querying [21] supports this type of mediation, and provides a basis for Delaunay MM 's future work in this area. With [9] providing a basis for future extensions to the Web. 5.2 Interface Design Similarly to [16], the intended user population of Delaunay MM is diverse, the types and views of information are unknown and the intended information space encompasses all media types. Unlike [16], this project does not have a sponsor to which the interface can be tailored. Although this distinction may not seem significant, the ability to support various information repositories with differing types of information is paramount to users of the World Wide Web. This distinction also increases the complexity of the interface, and the query creation and information retrieval mechanisms. Also, like [20], we seek to provide a global interface to distributed heterogeneous information, with an interactive user interface. Again, we differ from [20] in the scope of our application, as we are not limited to educational resources. [20] provides for additional functionality like the creation of a notebook metaphor or on-line editing, which would benefit some users of our application thus suggesting further work to incorporate these types of services. Delaunay MM 's approach is notably different from [13] because we deal with the display of multimedia query results, not presentations. One principle presented in [13] does extend to our model: the constraint-based layout methodology. The "Smart Interface", a focus of future work, could use this methodology to create virtual document layouts based on the results of a layout constraint solver. [7] 5.3 Information Organization Delaunay MM has selected an information organization structure, the keyword tree, that provides a great deal of flexibility for merging and manipulation. Although this structure adapts easily to our approach, other methods of information organization, such as ontologies and taxonomies, would be appropriate and offer other benefits, such as implied context through structure, that are worth exploration. These methods are not presently being explored because of the merging and manipulation complexity associated with them. Ontologies are developed to show the hierarchy or relationship between subject areas contained within a resource. While librarians generally use this structure to determine how to classify resources, end users may also benefit from understanding the structural relationships between their keywords and the Digital Library. As discussed in [22] ontology-based metadata supports precise queries and the creation of paths that lead from vague to precise and vice-versa, as well as other attributes. By utilizing the metadata inherently associated with ontological structure we expect to provide a context for queries not available through traditional search and retrieval mechanisms. A successful digital library architecture incorporates metadata [1,8] to allow effective searching and browsing of information. Because we provide a resident resource for pre-querying, the Metadata Warehouse, we are able to monitor and incorporate the ontologies of the information repositories into the structure, thus allowing metadata to be gathered implicitly through the ontology without requiring extraneous fields for holding metadata [10]. If we expand Delaunay MM 's approach to the World Wide Web, where there is no ontological pre-specified structure, and collaboration is not possible, such methods would be more suitable. 6. CONCLUSIONS AND FUTURE WORK Future efforts for Delaunay MM include the development of a "smart interface", integrating components with existing tools and projects, expanding the model toward World

7 Wide Web incorporation and solving multimedia retrieval optimization problems. Utilizing existing constraint solving tools, Delaunay MM hopes to provide more flexible layout customization and creation. At present layouts are based on static predefined templates; in the future, a move toward constraint-based dynamically created layouts is anticipated. The "smart interface" model uses a constraint template that contains relative positioning information to each virtual template. When objects are returned from a query, a constraint solver is used to determine what layout will best represent those objects, in effect providing a more dynamic interface. Similarly, including object relationship information, such as to_the_left, would also offer more accurate information presentation. We are presently focused on the interface, and hope to expand more of the back-end components. Thus, integrating our model with existing tools and projects that provide many of the back-end supporting technologies to the interface, is another area for emphasis. Exploring the World Wide Web as a supported information repository is another challenging area for future work. Finally, the retrieval of multimedia elements via the web is a costly process that requires optimization to increase overall usability. Because only a finite number of objects can be viewed at a time, developing a method to retrieve only that viewable fraction of objects would decrease the idle time between the query submission and the display of answers. Delaunay MM offers a flexible, customizable, user-centered approach to accessing distributed multimedia databases. The prototype has been implemented in Java [6], in conjunction with JDBC for database access. Usability studies have been done supporting the layout-centered approach, the interface, and methods of query specification. Thus far, the project has dealt primarily with the Perseus Project digital library, with continuing efforts being made to include more information repositories. 7. ACKNOWLEDGEMENTS We would like to thank Dave Brown for his involvement with the project, peerless insights, and support of this work, and Nastaran Baradaran in assisting with the development of the pre- and post-query refinement strategies. 8. REFERENCES [1] W. Arms, C. Blanchi, E. Overly. An Architecture for Information in Digital Libraries. D-Lib Magazine, February [2] G. R. Crane, ed. Building a Digital Library: the Perseus Project as a Case Study in the Humanities. First ACM International Conference on Digital Libraries, Pages 3-10, [3] I. F. Cruz and W. T. Lucas. A Customizable Layout- Drive Approach to Querying Digital Libraries. SPIE Multimedia Computing and Networking, Pages , [4] I. F. Cruz and W. T. Lucas. A Visual Approach to Multimedia Querying and Presentation. Fifth ACM International Multimedia Conference, Pages , [5] I.F. Cruz and K.M. James. Preserving Contextual Navigation in Hypermedia Querying. [Online] Available January 19, [6] I.F. Cruz, and K.M. James. A User-Centered Interface for Querying Distributed Multimedia Databases. ACM SIGMOD 99 (to appear). [7] I.F. Cruz and D.I. Lambe, Implementation of an Efficient Constraint Solver for the Layout of Graphs in Delaunay. Sixth Symposium on Graph Drawing Springer Verlag, [8] R. Daniel, C. Lagoze, S. Payette. A Metadata Architecture for Digital Libraries. IEEE International Forum on Advances in Digital Libraries Conference, Pages , [9] R. Dolin, D. Agrawal, J. Pearlman. Using Automated Classification for Summarizing and Selecting Heterogeneous Information Sources. D- Lib Magazine, January [10] A. Farquhar, R. Fikes, W. Pratt, & J. Rice. Collaborative Ontology Construction for Information Integration. Knowledge Systems Laboratory Department of Computer Science, KSL-95-63, August [11] J.C. French, A.L. Powell, and W.R. Creighton. Efficient searching in distributed digital libraries. Proceedings of the 3rd ACM Conference on Digital Libraries, Pages , [12] Georgia Tech Research Corporation. GVU s 9th WWW User Survey. [Online] Available /, October 9, [13] W. H. Graf. Towards a Reference Model for Intelligent Multimedia Layout. ECAI 96 Workshop Towards a Standard Reference Model for Intelligent Multimedia Systems. [14] S. Greene, et al. The End of Zero-Hit Queries: Query Previews for NASA s Global Change Master Dictionary. [Online] Available ftp://ftp.cs.umd.edu/pub/hcil/reports-abstracts- Bibliography/4856HTML/4856.html, January 8, 1998.

8 [15] S. Jones. Dynamic query result previews for a digital library. Third ACM Conference on Digital Libraries, Pages , [16] G. Marchionini, C. Plaisant and A. Komlodi. Interfaces and Tools for the Library of Congress National Digital Library Program. [Online] Available ftp://ftp.cs.umd.edu/pub/hcil/reports- Abstracts-Bibliography/3872HTML/3872.html, February 11, [17] C. Li, R. Yerneni, V. Vassalos, H. Garcia-Molina, Y. Papakonstantinou, J. Ullman, M. Valiveti. Capability Based Mediation in TSIMMIS. ACM SIGMOD 98, Pages , [18] B. Shneiderman. Designing the User Interface: Strategies for Effective Human-Computer Interaction. Addison Wesley Longman, Inc., [19] B. Shneidernman, D. Byrd, W. B. Croft. Clarifying Search: A User-Interface Framework for Text Searches. D-Lib Magazine, January [20] J. Takahashi, T. Kushida, J. Hong, R. Rieger, W. Martin, G. Gay, S. Sugita, Y. Kurita, J. Reeve, R. Loverance. Global Digital Museum: Multimedia Information Access and Creation on the Internet. Third ACM Conference on Digital libraries, Pages , [21] A.Tomasic, L.Raschid, and P. Valduriez. Scaling Access to Heterogeneous Data Sources with DISCO. IEEE Transactions on Knowledge and Data Engineering, Vol. 10, No. 5, September/October [22] P. Weinstein. Ontology-Based Metadata: Transforming the MARC Legacy. Proceedings of the Third ACM Conference on Digital libraries, Pages , [23] J. Widom. Research Problems in Data Warehousing. Fourth Conference on Information and Knowledge Management, Pages 25-30, Figure 2: Delaunay MM Query Specification Figure 4: Pre-Query Refinement (Search Assistant)

9 Figure 5: Post-Query Refinement (Refinement Assistant) Figure 6: Student/Research Virtual Page Format