15. A computer-implemented method for determining relevance, and for semantic search and personalized advertising based on association, comprising: receiving a topic or category name, wherein the topic or category name comprises a word or a phrase, wherein the topic or category name includes the name of a concept or object, or a product or service or activity or event; receiving a dataset related to the topic or category name, wherein the dataset comprises a plurality of property names representing a plurality of properties associated with the topic or category name, wherein there are at least two property names in the dataset each having an association strength value, wherein the plurality of property names are divided into a first group and a second group based on whether the association strength value is above or below a pre-defined threshold; receiving a text content containing one or more terms each comprising a word or a phrase; identifying a first term in the text content; and determining a relevance measure between the text content and the topic or category name based on whether the first term matches a property name in the first group or in the second group.
15. A computer-implemented method for determining relevance, and for semantic search and personalized advertising based on association, comprising: receiving a topic or category name, wherein the topic or category name comprises a word or a phrase, wherein the topic or category name includes the name of a concept or object, or a product or service or activity or event; receiving a dataset related to the topic or category name, wherein the dataset comprises a plurality of property names representing a plurality of properties associated with the topic or category name, wherein there are at least two property names in the dataset each having an association strength value, wherein the plurality of property names are divided into a first group and a second group based on whether the association strength value is above or below a pre-defined threshold; receiving a text content containing one or more terms each comprising a word or a phrase; identifying a first term in the text content; and determining a relevance measure between the text content and the topic or category name based on whether the first term matches a property name in the first group or in the second group. 20. The method of claim 15 , further comprising: displaying, in a user interface, the topic or category name.