I have an Erdös number of 4. This co-authorship graph shows some connections between mathematicians and HCI researchers:

                                        +--- Paul Erdos --------+
                                        |                       |
                         +-------- Maria M. Klawe -------+   Charles J. Colbourn
                         |              |                |      |
         Michael Chi Hung Wu   Joanna Lynn McGrenere -- Kellogg S. Booth
                 |         |                 |               |
      Ravin Balakrishnan   +------------ Ronald M. Baecker --+
          |            |                     |
Michael J. McGuffin   William A. S. Buxton --+