Kernel(s) for Problems with No Kernel: On Out-Trees with Many Leaves.

Henning Fernau Fedor V. Fomin Daniel Lokshtanov Daniel Raible Saket Saurabh Yngve Villanger Kernel(s) for Problems with No Kernel: On Out-Trees with Many Leaves. 421-432 2009 STACS http://drops.dagstuhl.de/opus/volltexte/2009/1843 conf/stacs/2009 db/conf/stacs/stacs2009.html#FernauFLRSV09