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Information Extraction -Introduction and Tools

2. Introduction. What is Information Extraction (IE) ?To select desired fields from the given data, by extracting common patterns that appear along with the information.To automate such a process.To make the process efficient by reducing the training data required, so as to restrict the cost.. 3.

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Information Extraction -Introduction and Tools

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    1. Information Extraction -Introduction and Tools V.G.Vinod Vydiswaran Roll no. 02329011 M.Tech (1st Year) KReSIT, IITBombay 29th October 2002 Guided by : Prof. S. Sarawagi

    2. 2 Introduction What is Information Extraction (IE) ? To select desired fields from the given data, by extracting common patterns that appear along with the information. To automate such a process. To make the process efficient by reducing the training data required, so as to restrict the cost.

    3. 3 Motivation Abundant online data available. Most IE systems specific to single information resource. IE models usually hand-coded, and hence error-prone. Data available either in structured form or in highly verbose content. Proper filters needed.

    4. 4 Types of Data Based on text styles: Structured data Semi-Structured text Plain text Based on information to the model: Labeled Unlabeled

    5. 5 Structured Data Relational Data Data in databases, in tables HTML Tags Query responses translated into Relational form using Wrappers Usually hand-coded and very specific to information resource

    6. 6 Wrapper Induction Wrapper Procedure extracting tuples from a particular information source A function from page to set of tuples Induction Task of generalizing from labeled examples to a hypothesis function of labeling instances

    7. 7 Wrapper Identification ExtractCCs (page P) { skip past first occurrence of <P> in P while next <B> is before next <HR> in P { for each (lk, rk) ? {(<B>,</B>), (<I>, </I>)} { skip past next occurrence of lk in P extract attribute from P to next occurrence of rk } } return extracted tuples } <HTML><HEAD> <TITLE>Country Codes</TITLE> </HEAD> <BODY> <B>Some Country Codes</B> <P> <B>Congo</B> <I>242</I><BR> <B>Egypt</B> <I>20</I><BR> <B>India</B> <I>91</I><BR> <B>Spain</B> <I>34</I><BR> <HR> <B>End</B> </BODY> </HTML>

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