1. A computer-implemented method for location name identification within document text, the computer-implemented method comprising performing computer-implemented operations for: receiving a document; detecting location names in the document; recognizing location senses of the detected location names, wherein the location senses comprise a possible meaning or context for each location name; organizing the recognized location senses together in a location sense hierarchy for the document comprising a location sense tree including observed location senses corresponding to location names detected within the document, and hidden location senses corresponding to location names not detected within the document but associated with the detected location names; performing the detection of location names and the recognition of location senses iteratively; determining a probability of each location name being an intended location, and determining a probability of each location name having a particular location sense; generating an initial relevance score for each observed location sense based on the probability of each location name being the intended location, a number of times the observed location sense appears in the given document; and generating a search index by propagating the relevance scores based on the initial relevance scores through the location sense tree such that the propagated relevance scores decay as they travel along branches of the location sense tree.
3. The computer-implemented method of claim 1 , wherein the search index associates a relevance of location senses to the document.