9. A computer system for identifying obsolete discussion threads in a forum comprising: a processor; a memory; and software instructions stored in the memory for causing the computer system to: extract a plurality of keywords from a discussion thread, wherein the discussion thread comprises a plurality of postings posted by a plurality of users; assign an initial keyword score to each of the plurality of keywords; identify a change event, wherein the change event is a change affecting a topic of the forum; extract a keyword from a recorded medium recording the change event, wherein the recorded medium is separate from the forum; compare the keyword from the recorded medium with the plurality of keywords from the discussion thread to identify a matching keyword in the plurality of keywords; decrease the initial keyword score of the matching keyword to a decreased score for the matching keyword based on the matching keyword matching the keyword from the recorded medium; aggregate the keyword score assigned to each of the plurality of keywords to obtain a total score for the discussion thread, wherein aggregating comprises using the reduced score for the matching keyword; and display a warning on a user interface comprising the discussion thread when the total score is below a first pre-specified threshold.
9. A computer system for identifying obsolete discussion threads in a forum comprising: a processor; a memory; and software instructions stored in the memory for causing the computer system to: extract a plurality of keywords from a discussion thread, wherein the discussion thread comprises a plurality of postings posted by a plurality of users; assign an initial keyword score to each of the plurality of keywords; identify a change event, wherein the change event is a change affecting a topic of the forum; extract a keyword from a recorded medium recording the change event, wherein the recorded medium is separate from the forum; compare the keyword from the recorded medium with the plurality of keywords from the discussion thread to identify a matching keyword in the plurality of keywords; decrease the initial keyword score of the matching keyword to a decreased score for the matching keyword based on the matching keyword matching the keyword from the recorded medium; aggregate the keyword score assigned to each of the plurality of keywords to obtain a total score for the discussion thread, wherein aggregating comprises using the reduced score for the matching keyword; and display a warning on a user interface comprising the discussion thread when the total score is below a first pre-specified threshold. 11. The computer system of claim 9 , wherein the initial keyword score of the matching keyword is decreased by subtracting a constant amount.