White - Machine Learning for Email

To explain the perspective from which this book was written, it will be helpful to define the terms machine learning and hackers .

What is machine learning? At the highest level of abstraction, we can think of machine learning as a set of tools and methods that attempt to infer patterns and extract insight from a record of the observable world. For example, if were trying to teach a computer to recognize the zip codes written on the fronts of envelopes, our data may consist of photographs of the envelopes along with a record of the zip code that each envelope was addressed to. That is, within some context we can take a record of the actions of our subjects, learn from this record, and then create a model of these activities that will inform our understanding of this context going forward. In practice, this requires data, and in contemporary applications this often means a lot of data (several terabytes). Most machine learning techniques take the availability of such a data set as givenwhich, in light of the quantities of data that are produced in the course of running modern companies, means new opportunities.

What is a hacker? Far from the stylized depictions of nefarious teenagers or Gibsonian cyber-punks portrayed in pop culture, we believe a hacker is someone who likes to solve problems and experiment with new technologies. If youve ever sat down with the latest OReilly book on a new computer language and knuckled out code until you were well past Hello, World, then youre a hacker. Or, if youve dismantled a new gadget until you understood the entire machinerys architecture, then we probably mean you, too. These pursuits are often undertaken for no other reason than to have gone through the process and gained some knowledge about the how and the why of an unknown technology.

Along with an innate curiosity for how things work and a desire to build, a computer hacker (as opposed to a car hacker, life hacker, food hacker, etc.) has experience with software design and development. This is someone who has written programs before, likely in many different languages. To a hacker, UNIX is not a four-letter word, and command-line navigation and bash operations may come as naturally as working with windowing operating systems. Using regular expressions and tools such as sed, awk and grep are a hackers first line of defense when dealing with text. In the chapters of this book, we will assume a relatively high level of this sort of knowledge.