AN ANALYSIS OF ‘IF’ SENTENCES FROM THE STANDPOINT OF COMMUNICATION’ Colleen Crangle2 and Patrick Suppes The challenge of ‘if‘ sentences This article examines ‘if‘ sentences and asks how one can explain the acceptability of one sentence over another in specific written contexts. It takes into account the temporal relations expressed in ‘if‘ sentences and the communicativeintentsthat lie behind their use. The analysis presented has its roots in our work on robots that understand English. We hold the strong conviction that the many subtle but clear distinctions that exist in English, such as those ex- pressed in ‘if‘ sentences, are there for good purpose. They have de- veloped historically and are used for effective and accurate com- munication. Although it may well be that our ultimate objective in communication with robots is to have the same completely free and sloppy use of language characteristic of spoken speech, a necessary first step toward this goal is to have robots understand the standard uses of English typically found in well-written text. It is in this framework that the analysis presented in this paper is conducted. Why are ‘if‘ sentences such a challenge in general to semantics? One reason is the wide range of complex notions they can be used to communicate. A recent issue of The Nm York Times Book Re- view (July 26, 1992) contains these examples. Notice not only what complex idea is being communicated in each case, but what specific temporal, logical, or causal relation is being described. (1) If I gave up the thing I loved most in the world, then maybe God (2) If local residents talk about Italy’s south, the word ‘Mafia’ is likely (3) If you keep a camera running too long mide a car, you’re (4) If the author did know hlm fairly well, you couldn’t tell from the would respect my desperation. to be heard. dead sketches presented in his book Journal of Literary Semantics, 22, 1993, pp. 1-23.