An important innovation in logical semantics was discourse representation theory (DRT) (Kamp 1981; Heim 1982), aimed at a systematic account of anaphora. In part, the goal was to provide a semantic explanation for (in)accessibility of NPs as referents of anaphoric pronouns, e.g., in contrasting examples such as “John doesn't drive a car; *he owns it,” vs.  “John drives a car; he owns it”. More importantly, the goal was to account for the puzzling semantics of sentences involving donkey anaphora, e.g.,  “If John owns a donkey, he beats it.” Not only is the NP a donkey, the object of the if-clause, accessible as referent of the anaphoric it, contrary to traditional syntactic binding theory (based on the notion of C-command), but furthermore we seem to obtain an interpretation of the type “John beats every donkey that he owns”, which cannot be obtained by “raising” the embedded indefinite a donkey to take scope over the entire sentence. There is also a weaker reading of the type, “If John owns a donkey, he beats a donkey that he owns”, and this reading also is not obtainable via any scope analysis. Kamp and Heim proposed a dynamic process of sentence interpretation in which a discourse representation structure (DRS) is built up incrementally. A DRS consists of a set of discourse referents (variables) and a set of conditions, where these conditions may be simple predications or equations over discourse referents, or certain logical combinations of DRS's (not of conditions). The DRS for the sentence under consideration can be written linearly as