Category Archives: Lecture Log

Lecture 15: Information Retrieval

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Slides : Music

Following the rectangular tables of relational databases and the triangular trees of semistructured data, the remaining Inf1-DA lectures will address the representation and analysis of more unstructured data. Today’s lecture provided a brief introduction to the classic information retrieval task of searching a large collection of documents to find those that match a simple query.
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Lecture 14: Example Corpora Applications

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Slides : Recording

Corpora are widely used for computational research into language, and for engineering natural-language computer systems. In linguistics, they make it possible to do real experimental science: to formulate hypotheses about the structure of languages, or changes in language between different places, times or people; and then test these on data. In building applications that handle text or speech, corpora provide the mass quantities of raw material used for machine learning and other algorithms.
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Lecture 12: Corpora

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Slides : Recording

In literature a corpus (plural corpora) is a collection of written texts, in particular the complete works of a single author or a body of writing on a single subject. In computational linguistics and in theoretical linguistics a corpus is a body of written or spoken text used for study of a particular language or language variety. These corpora may be very large (billions of words) and provide the raw material for experimental investigation of real-world language use: the science of empirical linguistics.
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Lecture 11: Navigating XML using XPath

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Slides : Recording

Once we have some semistructured data gathered into an XML tree, we might want to find information within it. For small XML documents we can just look at it, or use text search; for large and very large documents there are dedicated query languages. Today’s lecture presented one of them: XPath, the XML Path Language. As well as being a query language in its own right, XPath is also a key component of many other XML and web technologies, where it is used to navigate around documents.
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Lecture 10: Structuring XML

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Slides : Recording

Every well-formed XML document is neatly arranged as a tree, with names for element nodes and all their attributes. This is enough for basic tools to correctly transmit and process XML; but for many applications it is useful to add more precise domain-specific constraints that we expect documents to satisfy. For this we have XML schema languages: specialised languages for describing types of XML document. This lecture covered one in particular, the Document Type Definition language DTD.
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Lecture 9: Trees and XML

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Slides : Recording

From the strict rectangles of structured data to the more generous triangles of semistructured data. This morning’s lecture gave an overview of what kind of data is seen as “semistructured”; the idea of trees as a mathematical model of data; the particular form of trees in the XPath data model; and their textual representation in XML — the Extensible Markup Language.

XML also has a large number of domain-specific variants. These are all valid XML, and use standardised sets of element types to give a custom language for representing data relevant to a particular field: from musical scores to financial trading.
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