Information and communication
The central theme of this book is the representation of information in a formal and precise manner. We therefore have to try and describe what information is before we can go on and talk about its representation. Also, we need to indicate why we want to utilize a formal means of representation. We are all experts in the subject of information — we use it every day. Unfortunately, information is an intangible and it is difficult to talk about intangibles; most of the time we do not even think about such matters but rest comfortably with an intuitive feel for such things. Good question! According to Webster’s, information is, among other things, 1: The communication of or reception of knowledge or intelligence 2a: Knowledge obtained from investigation, study or instruction 2b: The attribute inherent in and communicated by one or two or more alternating sequences or arrangements of something (as nucleotides in DNA or binary digits in a computer program) that produces specific effects 2c: A signal or character (as in a communication system or computer) representing data. From the same source, we learn that data is Factual information (as measurements or statistics) used as a basis for reasoning, discussion, or calculation. The salient words that we are concerned with are knowledge, communication and data. In general we are concerned about information in the real world. To make matters more precise, we introduce our own definition of information. Definition 1 Information is knowledge of ideas, facts and/or processes. Information can be communicated, that is it may be transferred between two or more partners. (Strictly speaking, as the producer and user of information may be one and the same, only a single ‘partner’ may be involved.) This may be done in real time or there may be a delay between one partner sending the information and another receiving it. For example, the authors wrote this document long before anyone else read it. Consequently, information storage is just a special case of communication. The ultimate goal in information modeling is to formulate descriptions of real world information so that it may be processed and communicated efficiently without any knowledge of its source and without making any assumptions.