A mapping problem posed (informally) in 1985
and solved 27 years later,  in 2012:

See also Finite Relativity and Finite Relativity: The Triangular Version.

(A note for fans of the recent film Looper  (see previous post)—

Hunter S. Thompson in this journal on February 22, 2005 …

IMAGE- Hunter S. Thompson, the old and the young
           Hunter S. Thompson, photos from The New York Times

… and on March 3, 2009.)