Building the Memex Sixty Years Later: Trends and Directions in Personal Knowledge Bases ; CU-CS-997-05 (2005)

Software tools abound for managing documents and other information sources, but are rarely used for managing the personal, subjective knowledge an individual gleans from them.Yet for at least sixty years there has been a thread of interest in building a system to support a personalized repository of knowledge.This survey defines such systems as "personal knowledge bases," describes a number of important historical and recent examples, and gives a taxonomy of their principal characteristics.It concludes by broadly analyzing the design choices involved and sketching out an ideal solution. I. MotivationPersonal knowledge bases: toward Bush's Memex?Six decades have passed since the end of World War II, and also since the appearance of Vannevar Bush's ubiquitouslyquoted article "As We May Think" [Bush 1945] in the Atlantic Monthly.In it, Bush, President Truman's Director of Scientific Research, surveyed the post-war landscape and laid out what he viewed as the most important forthcoming challenges to humankind, even speculating as to possible solutions.The prophetic article presaged many technological changes, including the dawning of the information age.But undoubtedly his most intriguing idea -and in the years since, the most hotly pursued -was his vision of a hypothetical information storage device called the "Memex 2 ."This system was envisioned to tackle the "information overload" problem, already a formidable one in 1945.In Bush's own words: Consider a future device for individual use, which is a sort of mechanized private file and library.It needs a name, and to coin one at random, "memex" will do.A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility.It is an enlarged intimate supplement to his memory.As we will see, what Bush envisioned here was an early example of exactly what this survey will characterize as a personal knowledge base. Goals of this paper.In this survey we define the notion of a personal knowledge base (PKB) and explore the technological efforts researchers and inventors have made thus far towards creating one.It is a real and pressing problem, and an elusive one, as the sheer number of attempted solutions included in this survey attests.And we will argue that although certain aspects of the problem can be adequately met by existing software tools, the essential difficulty of capturing and retrieving personal knowledge is not completely solved by any of them.Rather, it appears that despite great gains over the last sixty years in office automation, distributed information networks, and applications for enhancing interaction with computers, today we still don't have a viable Memex as Bush envisioned.The Memex vision.Before delving into the survey proper, we wish to return briefly to Bush's article and note a few important points.His Memex is often cited as the precursor to today's hypertext systems ([Seyer 1991], [Nyce and Kahn 1991]) and indeed Doug Englebart and Ted Nelson, hypertext pioneers, have both acknowledged their debt to it ([Engelbart 1963], [Nelson 1987].)This is largely due to Bush's description of associative indexing, nearly identical to today's Web hyperlinks, through which the world's documents could be joined into a large associative network.Yet a careful reading of the article reveals a personalized dimension to the Memex that is very different than the public and collaborative focus of most hypertext efforts to date.Notice that the above quote specifies "individual use," and a "private file and library."And Bush's emphasis throughout the article was on expanding our own powers of recollection: "Man needs to mechanize his record more fully," he says, if he is not to "become bogged downby overtaxing his limited memory."To be sure, Bush envisioned collaborative aspects as well, and even a world-wide system that scientists could freely consult.But what is often ignored about his vision is this intensely personal aspect.With the Memex, the user can "add marginal notes and comments," and "build a trail of his interest" through the larger information space.He can share trails with friends, identify related works, and create personal annotations.A lawyer would have "at his touch the associated opinions and decisions of his whole experience," and similarly a doctor the records of his patients.In short, the Memex as Bush envisioned it would give each individual the ability to create, categorize, classify, and relate his own set of information corresponding to his unique personal viewpoint.Much of that information would in fact be comprised of bits and pieces from public documents, just as the majority of the knowledge inside our own heads has been imbibed from what we read and hear.But a monolithic Web of public documents is no substitute for the specialized recording of information that each individual perceives and needs to retain.The idea of "supplementing our memory" is not a one-size-fits-all proposition, since no two people have the same interests or opinions (or memories): it demands rather a subjective expression of knowledge, unique to each individual.Pursuit of a personal knowledge base.The personal Memex is needed more today than ever before.In fact, we contend that the ability for individuals to retain and reuse the knowledge they acquire is one of the key technological problems of the next decade.In some ways, the whole information revolution is useless without that component.What