6. The method of claim 1 wherein the topics and focuses of the questions of the collection are identified by generating a question tree of the questions of the collection and generating a cut of the question tree.
1. A method in a computing device for identifying questions relevant to a queried question, the method comprising: providing a collection of questions having terms, each question having a topic of one or more terms of the question and a focus of one or more terms of the question; for each topic and for each term in the questions of the collection, calculating by the computing device a probability of generating that term from a language model of that topic; for each focus and for each term in the questions of the collection, calculating by the computing device a probability of generating that term from a language model of that focus; receiving a queried question having terms; identifying a queried topic and a queried focus of the queried question; for each of a plurality of questions of the collection, calculating a topic probability of the queried topic as a probability of generating the terms of the queried topic from a language model of the topic of the question; calculating a focus probability of the queried focus as a probability of generating the terms of the queried focus from a language model of the focus of the question; and generating the probability of the queried question from a language model of the question using the calculated topic probability and the calculated focus probability of the question, the probability indicating the relevance of the question to the queried question.