exercise, left as an

from Jargon File (4.4.4, 14 Aug 2003)

exercise, left as an
 adj.

   [from technical books] Used to complete a proof when one doesn't mind
   a {handwave}, or to avoid one entirely. The complete phrase is: "The
   proof [or `the rest'] is left as an exercise for the reader." This
   comment has occasionally been attached to unsolved research problems
   by authors possessed of either an evil sense of humor or a vast faith
   in the capabilities of their audiences.

from The Free On-line Dictionary of Computing (8 July 2008)

exercise, left as an

   Used to complete a proof in technical books when one doesn't
   mind a {handwave}, or to avoid one entirely.  The complete
   phrase is: "The proof [or "the rest"] is left as an exercise
   for the reader."  This comment *has* occasionally been
   attached to unsolved research problems by authors possessed of
   either an evil sense of humour or a vast faith in the
   capabilities of their audiences.

   [{Jargon File}]

   (1995-02-20)

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