Handling implicit geographic evidence for geographic ir

Most geographic information retrieval systems depend on the detection and disambiguation of place names in documents, assuming that the documents with a specific geographic scope contain explicit place names in the text that are strongly related to the document scopes. However, some non-geographic names such as companies, monuments or sport events, may also provide indirect relevant evidence that can significantly contribute to the assignment of geographic scopes to documents. In this paper, we analyze the amount of implicit and explicit geographic evidence in newspaper documents, and measure its impact on geographic information retrieval by evaluating the performance of a retrieval system using the GeoCLEF evaluation data.