Figure 1 .

Excerpts from a discharge summary at various stages of the Negfinder pipeline. Top, Original document. Middle, Document transformed by coding of recognized concepts from UMLS 2000. Concepts are indicated by ~#:#:# where the three numbers indicate the UMLS concept ID, the byte offset in the text, and the length of the phrase. Thus, “pneumonia” is replaced by ~32285:17:9. The only words that remain are stop words and phrases or standard headings; unrecorded homonyms (see discussion in text) such as “rubs,”“S1,” and “S2”; and unrecorded variants of standard terms such as “gallop,” which is a variant of the UMLS preferred form “gallop rhythm.”Bottom, Negfinder mark-up simulated in monochrome. Negating phrases are marked in italics, identified concepts in bold; of these, negated concepts are also italicized.