11Classic Information Retrieval II2Modeling:“document”, “query”, “satisfying”(ignore “presenting in useful form” for now)Last time• Document is– Set of terms– Bag of terms– Sequence of termsContinue with• Query is ????3Modeling: “query”Continue with• Query– Basic query is one term– Multi-term query is• List of terms– OR model: some terms– AND model: all terms• Boolean combination of terms• Other constraints?4Modeling: “satisfying”• What determines if document satisfiesquery?• That depends ….– Document model– Query model• START SIMPLE– better understanding– Use components of simple model later5(pure) Boolean Model of IR• Document: set of terms• Query: boolean expression over terms• Satisfying:– Doc. evaluates to "true" onsingle-term query if contains term– Evaluate doc. on expression query as youwould any Boolean expression– doc satisfies query if evals to true on query6Boolean Model exampleDoc 1: “Computers have brought the world to our fingertips. We will try tounderstand at a basic level the science -- old and new -- underlying this newComputational Universe. Our quest takes us on a broad sweep of scientificknowledge and related technologies… Ultimately, this study makes us lookanew at ourselves -- our genome; language; music; "knowledge"; and, aboveall, the mystery of our intelligence. (cos 116 description)Doc 2: “An introduction to computer science in the context of scientific,engineering, and commercial applications. The goal of the course is to teachbasic principles and practical issues, while at the same time preparingstudents to use computers effectively for applications in computer science …”(cos 126 description)Query: (principles AND knowledge) OR (science AND engineering)27Boolean Model exampleDoc 1: “Computers have brought the world to our fingertips. We will try tounderstand at a basic level the science -- old and new -- underlying this newComputational Universe. Our quest takes us on a broad sweep of scientificknowledge and related technologies… Ultimately, this study makes us lookanew at ourselves -- our genome; language; music; "knowledge"; and, aboveall, the mystery of our intelligence. (cos 116 description)Doc 2: “An introduction to computer science in the context of scientific,engineering, and commercial applications. The goal of the course is to teachbasic principles and practical issues, while at the same time preparingstudents to use computers effectively for applications in computer science …”(cos 126 description)Query: (principles AND knowledge) OR (science AND engineering)Doc 1: 0 1 1 0 FALSE8Boolean Model exampleDoc 1: “Computers have brought the world to our fingertips. We will try tounderstand at a basic level the science -- old and new -- underlying this newComputational Universe. Our quest takes us on a broad sweep of scientificknowledge and related technologies… Ultimately, this study makes us lookanew at ourselves -- our genome; language; music; "knowledge"; and, aboveall, the mystery of our intelligence. (cos 116 description)Doc 2: “An introduction to computer science in the context of scientific,engineering, and commercial applications. The goal of the course is to teachbasic principles and practical issues, while at the same time preparingstudents to use computers effectively for applications in computer science …”(cos 126 description)Query: (principles AND knowledge) OR (science AND engineering)Doc 2: 1 0 1 1 TRUE9Boolean Model exampleDoc 1: “Computers have brought the world to our fingertips. We will try tounderstand at a basic level the science -- old and new -- underlying this newComputational Universe. Our quest takes us on a broad sweep of scientificknowledge and related technologies… Ultimately, this study makes us lookanew at ourselves -- our genome; language; music; "knowledge"; and, aboveall, the mystery of our intelligence. (cos 116 description)Doc 2: “An introduction to computer science in the context of scientific,engineering, and commercial applications. The goal of the course is to teachbasic principles and practical issues, while at the same time preparingstudents to use computers effectively for applications in computer science …”(cos 126 description)Query: (principles OR knowledge) AND (science AND NOT(engineering))10Boolean Model exampleDoc 1: “Computers have brought the world to our fingertips. We will try tounderstand at a basic level the science -- old and new -- underlying this newComputational Universe. Our quest takes us on a broad sweep of scientificknowledge and related technologies… Ultimately, this study makes us lookanew at ourselves -- our genome; language; music; "knowledge"; and, aboveall, the mystery of our intelligence. (cos 116 description)Doc 2: “An introduction to computer science in the context of scientific,engineering, and commercial applications. The goal of the course is to teachbasic principles and practical issues, while at the same time preparingstudents to use computers effectively for applications in computer science …”(cos 126 description)Query: (principles OR knowledge) AND (science AND NOT(engineering))Doc 1: 0 1 1 0 TRUE11Boolean Model exampleDoc 1: “Computers have brought the world to our fingertips. We will try tounderstand at a basic level the science -- old and new -- underlying this newComputational Universe. Our quest takes us on a broad sweep of scientificknowledge and related technologies… Ultimately, this study makes us lookanew at ourselves -- our genome; language; music; "knowledge"; and, aboveall, the mystery of our intelligence. (cos 116 description)Doc 2: “An introduction to computer science in the context of scientific,engineering, and commercial applications. The goal of the course is to teachbasic principles and practical issues, while at the same time preparingstudents to use computers effectively for applications in computer science …”(cos 126 description)Query: (principles OR knowledge) AND (science AND NOT(engineering))Doc 2: 1 0 1 1 FALSE12(pure) Boolean