15. A system comprising a computer having a processor and a data storage, the processor being programmed to perform the following acts: identifying appearances of a plurality of geographical names in a document; determining one or more frequencies of each geographical name's appearances in the document, the plurality of geographical names including a first geographical name and a second geographical name; assigning one or more positional weights to the first geographical name according to positions of the first geographical name's appearances in the document, the assigning including: identifying one or more position types where the first geographical name appears in the document, assigning a same position type to a first instance of the first geographical name and a first instance of the second geographical name in response to determining that the first instance of the first geographical name and the first instance of the second geographical name are within a same paragraph of the document; and assigning a respective positional weight to each position type where the first geographical name appears in the document; computing a score of the first geographical name based on the one or more frequencies and the one or more positional weights of the first geographical name.
15. A system comprising a computer having a processor and a data storage, the processor being programmed to perform the following acts: identifying appearances of a plurality of geographical names in a document; determining one or more frequencies of each geographical name's appearances in the document, the plurality of geographical names including a first geographical name and a second geographical name; assigning one or more positional weights to the first geographical name according to positions of the first geographical name's appearances in the document, the assigning including: identifying one or more position types where the first geographical name appears in the document, assigning a same position type to a first instance of the first geographical name and a first instance of the second geographical name in response to determining that the first instance of the first geographical name and the first instance of the second geographical name are within a same paragraph of the document; and assigning a respective positional weight to each position type where the first geographical name appears in the document; computing a score of the first geographical name based on the one or more frequencies and the one or more positional weights of the first geographical name. 21. The system as recited in claim 15 , wherein the acts further comprise determining core geographical information in the document based on scores of the plurality of geographical names, the determining including: identifying a highest scoring geographical name among the plurality of geographical names; and taking the highest scoring geographical name to be the core geographical information of the document.