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6.1. Fact models: an overview > 6.1.8. Facts and fact types - Pg. 149

128 CHAPTER 6 Fact models 6.1.8 Facts and fact types An organization's understanding of its environment is achieved through the assembly of various facts of interest. To an airline, Frequent Flier #123456 resides in Sydney, Frequent Flier #234567 resides in Melbourne, and Frequent Flier #345678 resides in Brisbane are all facts that can be used, say, for marketing or tailoring the online experience of frequent flier program members. Similarly, Flight QF1 operates from Sydney to London Heathrow, Flight QF765 operates from Sydney to Adelaide, and Flight QF926 operates from Sydney to Cairns are all facts that can be used both by the airline and its customers to identify services available between particular cities. In each case, the organization has established multiple facts of the same type: in the first case each fact is of the form depicted in F13, while in the second case each fact is of the form depicted in F14. F13. frequent flier program member resides in city F14. flight operates from port to port Since these forms are archetypes of similar facts, we can call them fact types. Specifically, they are both associative fact types, since they each provide a pro forma for one or more associative facts, namely facts that associate phenomena with each other: for example, people with the cities in which they re- side, and flights with ports. Each fact type includes 1. terms (frequent flier program member, city, flight, port), which act as placeholders, in place of which can be substituted the name of any member of the set signified by the term; 2. a fact symbol (`resides in', `operates from . . . to'), which consists of everything in the fact type other than the terms. Each fact symbol consists of one or more connectors, each being a contiguous set of words, either a verb phrase or a preposition. Thus F13's fact symbol consists of the connector `resides in' while F14's consists of the two connectors `operates from' and `to'. Fact types are discussed in more detail in Section 6.3. 6.1.9 Identification To be able to express the facts in the previous section, an organization needs to have a means of iden- tifying individual persons, cities, flights, and ports. Indeed, to express any fact of interest, one must be able to identify individual instances of each concept of interest. To be able to do this, the organization needs a reference scheme for each set of concepts of interest, namely one or more numbers, names, or codes that together uniquely identify each instance of the concept. In the case of frequent flier program members, the membership number is sufficient since presum- ably no number has been allocated to more than one member. Of course, if the airline provides recip- rocal services to members of allied airlines' frequent flier programs, the membership number alone is