Resumen de Whitney's extension problem for C^m
Charles L. Fefferman 
Let f be a real-valued function on a compact set in Rn, and let m be a positive integer. We show how to decide whether f extends to a Cm function on Rn.
Charles L. Fefferman
Let f be a real-valued function on a compact set in Rn, and let m be a positive integer. We show how to decide whether f extends to a Cm function on Rn.
