MODEL 1: A Poem by John Godfrey Saxe ( ) THE BLIND MEN AND THE ELEPHANT

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Janice Whitehead
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1 Searching Text pg 1 of 6 MODEL 1: A Poem by John Godfrey Saxe ( ) THE BLIND MEN AND THE ELEPHANT 1 It was six men of Indostan 31 The Fifth, who chanced to touch the ear, 2 To learning much inclined, 32 Said: "E'en the blindest man 3 Who went to see the Elephant 33 Can tell what this resembles most; 4 (Though all of them were blind), 34 Deny the fact who can, 5 That each by observation 35 This marvel of an Elephant 6 Might satisfy his mind. 36 Is very like a fan!" 7 The First approach'd the Elephant, 37 The Sixth no sooner had begun 8 And happening to fall 38 About the beast to grope, 9 Against his broad and sturdy side, 39 Then, seizing on the swinging tail 10 At once began to bawl: 40 That fell within his scope, 11 "God bless me! but the Elephant 41 "I see," quoth he, "the Elephant 12 Is very like a wall!" 42 Is very like a rope!" 13 The Second, feeling of the tusk, 43 And so these men of Indostan 14 Cried, "Ho! what have we here 44 Disputed loud and long, 15 So very round and smooth and sharp? 45 Each in his own opinion 16 To me 'tis mighty clear 46 Exceeding stiff and strong, 17 This wonder of an Elephant 47 Though each was partly in the right, 18 Is very like a spear!" 48 And all were in the wrong! 19 The Third approached the animal, 20 And happening to take 21 The squirming trunk within his hands, 22 Thus boldly up and spake: 23 "I see," quoth he, "the Elephant 24 Is very like a snake!" MORAL: 25 The Fourth reached out his eager hand, 49 So oft in theologic wars, 26 And felt about the knee. 50 The disputants, I ween, 27 "What most this wondrous beast is like 51 Rail on in utter ignorance 28 Is mighty plain," quoth he, 52 Of what each other mean, 29 "'Tis clear enough the Elephant 53 And prate about an Elephant 30 Is very like a tree!" 54 Not one of them has seen!

2 Searching Text pg 2 of 6 Model 2 Page 1 Page 2 Computer science is the study of the "The Last Question" is a science fiction theory, experimentation, and engineering short story by American writer Isaac that form the basis for the design and use Asimov. It first appeared in the November of computers issue of Science Fiction. A succinct definition of computer science is the study of automating algorithmic processes that scale. A computer scientist specializes in the theory of computation and the design of computational systems. Source: Wikipedia It was Asimov's favorite short story of his own authorship, and is one of a loosely connected series of stories concerning a fictional computer called Multivac. The story overlaps science fiction, theology, and philosophy. Source: Wikipedia Model 3 Search Index... called: 2-50 computation: 1-46 computational: 1-51 computer: computers: 1-22 concerning: question: 2-3 scale: 1-37 science: scientist: 1-40 series: 2-43 short: specializes:

3 Searching Text pg 3 of 6 Searching Text This activity explores how search engines use indexes to speed up searching and to rank search results. I. Full Text vs Indexed Search 1. Model 1 has a poem by John Saxe. For each of the following questions, have the Reader count off the number of seconds it takes the rest of the team to answer the question. (A rough count of one one-thousand, two one-thousand, three one-thousand is fine). Record the answer and how long it took to find the answer: Question Answer Time a. Does the word Indostan appear in the poem? b. What is the second word in the poem? c. Does the word tiger appear in the poem? d. How many times does the word Elephant appear in the poem? INFORMATION : At a basic level, full text search is the process of going through the entire text one word at a time, and deciding whether each word is the right one. 2. Which parts (a, b, c, d) from question 1 required full text search?

4 Searching Text pg 4 of 6 INFORMATION : An index for a document lists where certain words can be found. As we look for particular terms, we could build an index with what we find. Here is a partial index for The Blind Men and The Elephant: search word location beast line 27, word 5 line 38, word 3 blind line 22, word 3 Indostan line 1, word 6 line 43, word 6 monkey not found six line 1, word 3 snake line 24, word 5 3. How is the index organized? Why is this important? 4. Which of the following searches will be faster using that index than the full text? Question a. Does the word snake appear in the poem? b. How many times does Indostan appear? c. What is the third word of the poem? d. Is the word beast on line 38? Faster? 5. Why is it useful to cache searches that are "not found" (such as monkey)? 6. Give one or more disadvantages to building an index. 7. Instead of building an index as we go, we could pre-index the entire poem by building an index that contains every word in the poem. Why would this approach only make sense if we were going to ask many questions about the poem? 8. Would we need to include "not found" items in our pre-index? Why or why not?

5 Searching Text pg 5 of 6 II. Filtering & Ranking Web search engines attempt to build an index of all the pages on the Web. When a user submits a query (a search request) the search engine uses that index to identify which pages match the query. They then attempt to rank the results to put the best matches first. In this section we will explore how identifying matches and ranking them works. Query Builds Index Commented [AS1]: Only loosely based on Search 2. The critical idea I need students to wrestle with is how a page-word index works and how it can be used for filtering, ranking and neat tricks like phrase searches. User Search Engine Web Results We will be looking at excerpts from two Wikipedia pages. Before starting this activity, independently read the two "pages" in Model 2. Once everyone is done reading, continue with the questions below. 1. Which page would be a better source for someone trying to learn about the term computer science? Describe why you think it is a better source. INFORMATION : Search engines build indexes for all the pages they know about. Model 3 is an index for the two web pages from Model 2 (some words have been omitted to make it easier for you to read). In this index, we are keeping track of page-word pairs. (We are not tracking line numbers.) For example, the line: is: Indicates that is is the 3 rd word on page 1, the 29 th word on page 1, and is the 4 th and 37 th word on page On which page does the index in Model 3 say the word question appears? 3. How many times does the word short appear on Page 2? 4. What do you notice about the index entry for the word computer? 5. What do you notice about the index entry for the word science?

6 Searching Text pg 6 of 6 6. Using only the information in the index, how might you guess which page is a better match for the word computer? 7. Using only the information in the index, how might you guess which page is a better match for science? INFORMATION: When you do a google search, it shows you the number of results at the top of the page. (As seen to the right for a search on "cat" which produces over 2 billion results). 8. Do three separate google searches and record the number of results for the search queries shown below. Query a) science computer b) computer science c) "computer science" # Results Commented [AS2]: Based on original, but I don t need them to go into logical operators yet want to really drill in on how phrase search can be performed. 9. What are some reasons that a search for science computer might return a different list of results from computer science? 10. Describe what you notice about the results for searching for computer science versus searching for "computer science" (with quotes). 11. In page 2 from Model 2, the word scientist comes right before the word specializes. How can you tell that only by using what is in the index (Model 3)? 12. Search engines assume a search for "computer science" means you want to see that exact phrase (the words, in order, directly next to each other). Using only the index, how can you tell on which page the word computer appears right before the word science?

Why study computer networks? 1: Introduction. Goals of this class. How much do you know already? How do we begin to make sense of the Internet?

Why study computer networks? 1: Introduction Last Modified: 1/27/2003 1:25:26 PM They are engineering marvels! Scalability, layered protocols, lots of subtleties- worthy of study They are all around us!