Minimization of Decision Trees Is Hard to Approximate.

Detlef Sieling Minimization of Decision Trees Is Hard to Approximate. 84-92 2003 conf/coco/2003 IEEE Conference on Computational Complexity http://csdl.computer.org/comp/proceedings/complexity/2003/1879/00/18790084s.htm db/conf/coco/coco2003.html#Sieling03