Information and Architecture

1 Incremental and reeexive information Elwood lies on a hospital bed, a thermometer|we'll call it t|in his mouth. Bad news about Elwood: (1) The fact that the mercury in t is above 98.6 carries the information that Elwood has a fever. The fact referred to we call the signal or indicating fact. The thermometer is the carrier of the signal, the property of containing mercury that has risen past 98.6 is the indicating property. The proposition that Elwood has a fever is the incremental informational content of the signal. The property of having a fever is the indicated property; Elwood is the subject matter of the proposition that is the content, and derivatively, of the signal. A signal has incremental content, given a connecting fact and relative to a constraint. 1 In this case, the connecting fact is that the thermometer is in Elwood's mouth, the connecting relation is that of one thing being in the mouth of another, and the constraint C 1 is: (C 1) Given that a thermometer is in a person's mouth, if the mercury goes above 98.6, that person has a fever. research reported in this paper has been made possible by a gift from the System Development Foundation. 1 This paper is a continuation of 1] and builds on both the theory and the terminology of that earlier work. However, our treatment of reeexive content is diierent.