Information Retrieval

Can you explain the graph again about why the graph is constructed like that?

Is the length of the doc affect the effactive of the probability of the generating strings?

Based on the tf-idf weighting, how can we use the result of the term in the practice?  And how to evaluate the performance of the work using that or how to know it works? Also, I am still confused about the computing of cosine scores.

Why boolean search using AND operations tends to produce high precision but low recall searches, while using OR operators gives low precision but high recall searches?

If we don't know the distribution of the key-value pairs in a new collection, how to do the MapReduce? I'm confused with the punctuations "/" and "-"

·        IIR sections 1.2, chapters 2 and 3 In the section 1.2 A first take at building an inverted index, I learn the major steps in build the index.  1)collect the documents to be indexed 2)tokenize the text, turning each document into a list of tokens 3)do linguistic preprocessing, producing a list of normalized tokens, which are the indexing terms 4)index the documents that each term occurs in by creating an inverted index, consisting of a dictionary and postings In the chapter 2 the term vocabulary and postings lists. I learnd that the first step of processing is to convert this byte sequence into a linear sequence of characters. And the next phase is to determine what the document unit for indexing is. What's more, we should given a character swquence and a defined documnet unit, tokenization is the task of chopping it up into pieces, called tokens, perhaps at the same time throwing away certain characters, such as punctuation. Th...

·        FOA section 1.1 By reading the FOA, I learn that the book is a closer look at the process of finding out about, reserch activities that allow a decision-maker to draw on others' knowledge. And the FOA process of browsing readers can be imagined to involve three phases : 1) asking a question 2) constructing an answer 3) assessing the answer. What's more,  give the schematic of search engine. ·        IES section 1.1 and 1.2 I learned that information retriveval is concerned with representingm searching, and manip ulating large collections of electronic text and other human-language data.In detail, I learn about the web search, desktop and file system search and how others IR applications works associated wi th the storage, manipulation, and retrieval of human-language data.Then, I learn the basic IR system architecture, the components of an IR system. What's more, the update and modify of the documents. And ...