15. A system for determining core geographical information in a document, the system comprises 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 the document; determining one or more frequencies of each geographical name's appearances in the document; assigning one or more positional weights to each geographical name according to positions of the geographical name's appearances in the document; computing a score of a respective geographical name based on the one or more frequencies and the one or more positional weights of the respective geographical name, the computing including: in response to determining that the respective geographical name appears conjunctively or consecutively with another geographical name in the document, increasing a score of the respective geographical name and a score of the another geographical name; and determining the core geographical information in the document based on scores of the plurality of geographical names.
15. A system for determining core geographical information in a document, the system comprises 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 the document; determining one or more frequencies of each geographical name's appearances in the document; assigning one or more positional weights to each geographical name according to positions of the geographical name's appearances in the document; computing a score of a respective geographical name based on the one or more frequencies and the one or more positional weights of the respective geographical name, the computing including: in response to determining that the respective geographical name appears conjunctively or consecutively with another geographical name in the document, increasing a score of the respective geographical name and a score of the another geographical name; and determining the core geographical information in the document based on scores of the plurality of geographical names. 18. The method as recited in claim 15 , wherein the computer is a server connected to the Internet.