Topic Maps and Global Knowledge Interchange
- Information Is Interesting Stuff
- Information and Structure Are Inseparable
- Formal Languages Are Easier to Compute Than Natural Languages
- Generic Markup Makes Natural Languages More Formal
- A Brief History of the Topic Maps Paradigm
- Data and Metadata: The Resource-Centric View
- Subjects and Data: The Subject-Centric View
- Understanding Sophisticated Markup Vocabularies
- The Topic Maps Attitude
In 1989, Yuri Rubinsky1 made a video that he hoped would compel any viewer to grasp the importance of SGML, the ISO standard metalanguage from which has come much of the "Internet revolution," including HTML and XML. The intent of the video was to dramatize the enormous significance of a simple but revolutionary idea: any informationany informationcan be marked up in such a way as to be parsable (understandable, in a certain basic sense) by a single, standard piece of software, by any computer application, and even by human readers using their eyes and brains.
In the video, aliens from outer space understand a message sent from Earth, because the message is encoded in SGML. This little drama occurs after the aliens first misunderstand a non-SGML message from Earth. (They have already eaten the first message, believing it to be a piece of toast.)
At the time, I was having great difficulty helping my colleagues understand the nature of my work, and I thought maybe Yuri's video would help. One of my colleagues, who had funding authority over my work, was surprised that I had never explained to him that the purpose of my work was to foster better communications between humans and aliens. He was quite serious.2
This experience and many others over the years have convinced me that, while the technical means whereby true global information interchange can be achieved are well within our grasp, there are significant anthropological obstacles. For one thing, it's very challenging to interchange information about information interchange. As human beings, we pride ourselves on our ability to communicate symbolically with each other, but comparatively few of us want to understand the details of the process. Communication about communication requires great precision on the part of the speaker and an unusually high level of effort on the part of the listener. I suspect that this is related to the fact that many people become uncomfortable or lost when the subject of conversation is at the top of a heap of abstractions that is many layers thick. It's an effort to climb to the top, and successful climbs usually follow one or more unsuccessful attempts.
When you have mastered the heap of abstractions that must be mastered in order to understand how global information interchange can be realized, the reward is very great. The view from the top is magnificent. From a technical point of view, the whole problem becomes simple. Very soon thereafter, however, successful climbers realize that they can't communicate with nonclimbers about their discoveries. This peculiar inability and its association with working atop a tall heap of abstractions are evocative of the biblical myth of the Tower of Babel. Successful abstraction-heap climbers soon find themselves wondering why their otherwise perfectly reasonable and intelligent conversational partners can't understand simple, carefully phrased sentences that say exactly what they're meant to say.
You have now been warned. This book is about the topic maps paradigm, which itself is a reflection of a specific set of attitudes about the nature of information, communication, and reality. Reading this book may be quite rewarding, but there may also be disturbing consequences. Your thinking, your communications with others, and even your grasp of reality may be affected.3
Information Is Interesting Stuff
Information is both more and less real than the material universe. It's more real because it will survive any physical change; it will outlast any physical manifestation of itself. It's less real because it's ineffable. For example, you can touch a shoe, but you can't touch the notion of "shoe-ness" (that is, what it means to be a shoe). The notion of shoe-ness is probably eternal, but every shoe is ephemeral.
The relationship between information and reality is fascinating. (By reality here I mean "the reality of the material universe"or what we think of as its reality.) We all behave as if we believe that there is a very strong, utterly reliable connection between information and reality. We ascribe moral significance to the idea that information can be true or false: we say that it's true when it reflects reality and false when it doesn't. However, there is no way to prove or disprove that there is any solid, objective connection between symbols and reality. Symbols are in one universe, reality is in another; human intuition, understanding, and belief form the only bridge across the gap between the two universes. The universe of symbols is a human invention, and our arts and sciencesthe information resources that human civilization has accumulatedare the most compelling reflection of who and what we are.
Money, the "alienated essence of work" as some philosophers have put it, is also information. I once saw Jon Bosak4 hold up a dollar bill in front of an XML-aware technical audience, saying, "This is an interesting document." The huge emphasis that our culture places on the acquisition of money is a powerful demonstration of our confidence in the power of information to reflect reality or, more accurately, in the power of information to affect reality. In the United States, we have a priesthood called the Federal Reserve Board, answerable to no one, whose responsibility is to protect and maximize the power of U.S. dollars to affect reality. The Fed seeks to control monetary inflation, for example, because inflation represents a diminishment of that power.
Thinking of money as a class of information suggests an illustration of the importance of context to the significance of information for individuals and communities: given the choice, most of us prefer money to be in the context of our own bank accounts. Thinking of money as information leads one to wonder whether information and money in some sense are the same thing. Some information commands a very large amount of money, and the visions of venture capitalists and futurists are often based on such intellectual property. In some circles, the term information economy has become a pious expression among those who are called upon to increase shareholder value. (On the other hand, the economic importance of information can be overstressed. Information when eaten is not nourishing, and when it is put into fuel tanks, it does not make engines run.)
Information has far too many strange and wonderful aspects to allow them all to be discussed here; I regret that I can only mention in passing the mind-boggling insights offered by recent research in quantum physics, for example.
For purposes of this writing, anyway, the most interesting aspect of information is the unfathomable relationship between information and the material universe, as well as the assumptions we all make about that relationship in order to maintain our global civilization and economy. That unfathomable relationship profoundly influenced the design of the topic maps paradigm. Those who would understand the topic maps paradigm must appreciate that there is some sort of chasm between the universe of information (that is, the world of human-interpretable expressions) and the universe of subjects that information is abouta chasm that is (today, anyway) bridgeable only by human intuition, not by computers. The topic maps paradigm recognizes, adapts itself to, and exploits this chasm. (We'll discuss this later.)