Is that possible? Haven't found the token combination yet. Any ideas?

I'd like my drupal advanced forum URLs to be generated as /forum//, e.g. /forum/social_science/us_history. If I include the forum container, it would be something like /forum/social_science_forums/social_science/us_history. Seems redundant and not very clean.

Do I have any options here? I'd like to include the containers for a visual/layout point of view, just not include them in the URLs.

Thanks,
-Chris