01: Semantic Web Vision & Structured Web Documents in XML Flashcards
What are the problems with the current keyword-based search engines?
- Key Problem: the meaning of Web content is not machine-accessible: a lack of semantics
- High recall, low precision
- Low or no recall
- Results are highly sensitive to vocabulary
- Results are single Web pages
- Human involvement is necessary to interpret and combine results
- Results of Web searches are not readily accessible by other software tools
What are the three key points with Semantic Web approach?
- Representing Web content in a form that is more easily machine-processable
- Using intelligent techniques to take advantage of these representations
- Evolving out of the existing Web
What are the limitations of current knowledge management technologies in four dimensions?
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Searching information
- Keyword-based search engines
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Extracting information
- Human involvement necessary for browsing, retrieving, interpreting, combining
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Maintaining information
- Inconsistencies in terminology, outdated information
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Viewing information
- Impossible to define views on Web knowledge
What are the characteristics of a Semantic Web Enabled knowledge management?
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Advantages:
- Organizing knowledge in conceptual spaces according to its meaning
- Having automated tools for maintenance and knowledge discovery
- Answering any query semantically
- Answering any query over several documents
- Defining who may view certain parts of information (even parts of documents) will be possible
What are the benefits of Web Enabled B2B electronic commerce?
- Businesses enter partnerships without much overhead
- Differences in terminology will be resolved using standard abstract domain models
- Data will be interchanged using translation services
- Auctioning, negotiations, and drafting contracts will be carried out automatically (or semi-automatically) by software agents
What are some problems with HTML?
- Humans don’t have an issue, but machines (software agents) do
- How to distinguish “therapists” for a “secretary”?
- How to determine exact consultation hours?
- They would have to follow the link to the State of Origin games to find when they take place
- XML would be a better representation
What is explicit metadata?
“Data about data”–metadata capture part of the meaning of data
What is an ontology?
An explicit and formal specification of a conceptualization
What are the typical components of an ontology?
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Terms denote important concepts (classes of objects) of the domain
- e.g. professors, staff, students, courses, departments
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Relationships between these terms: typically class hierarchies
- A class C to be a subclass of another class C’ if every object in C is also included in C’
- e.g. All professors are staff members
Draw an example of a class hierarchy.
What is the role of ontologies on the Web?
- Ontologies provide a shared understanding of a domain: semantic interoperability
- Overcome differences in terminology
- Mappings between ontologies
- Useful for the organization and navigation of Web sites
- Useful for improving the accuracy of Web searches
- Web searches can exploit generalization/specialization information
What is the tradeoff between expressive power and computation complexity?
The more expressive a logic is, the more computationally expensive it becomes to draw conclusions
What are software agents?
- Work autonomously and proactively
- Evolved out of object-oriented and component-based programming
What will a personal agent on the Semantic Web do? Name its operations one after another chronically (in a time-based sequence).
- Receive some tasks and preferences from the person
- Seek information from Web sources, communicate with other agents
- Compare information about user requirements and preferences, make certain choices
- Give answers to the user
What are the principles of a layered approach to the development of the Semantic Web?
- Downward compatibility
- Upward partial understanding
Draw the general Semantic Web layer stack.
Draw the specific Semantic Web layer stack.
Provide an example of a meaningful empty element in XML.
- An empty element is not inherently meaningless
- It may have some properties in terms of attributes
- An attribute is a name-value pair inside the opening tag of an element
What is a comment and how would you write one in XML?
A piece of text that is to be ignored by the parser
How do you declare a namespace?
Can be declared within an element and can be used in that element and any of its children
