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This is a digital copy of a book that was preserved for generations on libraryshelves before it was carefully scanned by Google as part of a project to makethe world's books discoverable online. It has survived long enough for thecopyright to expire and the book to enter the public domain. A public domainbook is one that was never subject to copyright or whose legal copyright termhas expired. Whether a book is in the public domain may vary country tocountry. Public domain books are our gateways to the past, representing awealth of history, culture and knowledge that's often difficult to discover.Marks, notations and other marginalia present in the original volume may appearin this file - a reminder of this book's long journey from the publisher to alibrary and finally to you. Google Book Search has digitized millions of physical books and made themavailable online at http://books.google.com. The digitization at the most basic level is based on page images of thephysical books. To make this book available as an ePub formated file we havetaken those page images and extracted the text using Optical CharacterRecognition (or OCR for short) technology. The extraction of text from pageimages is a difficult engineering task. Smudges on the physical books' pages,fancy fonts, old fonts, torn pages, etc. can all lead to errors in theextracted text. Imperfect OCR is only the first challenge in the ultimate goalof moving from collections of page images to extracted-text based books. Ourcomputer algorithms also have to automatically determine the structure of thebook (what are the headers and footers, where images are placed, whether textis verse or prose, and so forth). Getting this rightallows us to render thebook in a way that follows the format of the original book. Despite our best ...
