Similarity-Based Object Metadata

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Progress ReportRod McFarland

CPSC 533C

Outline Background Problem Concept Concept Development Implementation Demonstration Future Enhancements

Background UBC Learning Object Metadata Repository

What is a Learning Object? Not what we usually consider “objects” to be

Metadata Specifications: IMS, CanCore XML schema for describing objects

Web-based client interface (JSP/XML/MySQL) http://flora.cs.ubc.ca:8080/learningobject

Problem Metadata provides flexible and

comprehensive descriptions of general objects

Traditional search interfaces tend to offer searching on only a few descriptive dimensions

CanCore metadata specification has 41 non-placeholder elements – any of these could potentially be searchable

Concept Use a browsing strategy based on

“similarity” to a known object Define “similarity”

Depends on the data type (Language strings, dates, pure number, standard vocabularies)

How to handle varying multiplicity among metadata records

Selection of known object Via conventional text-based search Via specification of “ideal” object

Concept Originally envisioned a network view with

pairs of objects of nonzero similarity linked by lines of length inversely proportional to the similarity. A bit of thought shows that this won’t work –

without a lot of work, “similarity” is not a metric

New idea: similar objects radially arranged around known object, with distance inversely proportional to similarity

Concept Development Similarity can be adjusted. As an

aggregate measure, the component similarities can be given different weights

Selecting objects in the “cloud” will change the focus object and cause a new display to be generated

A “path” through the object space can indicate what objects have been visited

Implementation Intended to be embedded in a Web page,

so development will be in Java/Swing Few available LO records, so modifying

project to use a different source of objects (sentences in a text file) Since this was not intended to be a text

browser, not offering a full-text view

[demo]

Future Enhancements (soliciting opinions and suggestions) Prototype object to specify initial search focus Color coding of dots to indicate most related dimension Animated transition on focus object change Make the “visited path” feature more useful – how? Single-click or hover over object to see metadata detail Change scale of display (by dragging mouse away from

centre) How to handle “ghost” objects Negative weighting Multiple options for computing similarity for a data type