Claudette Cayrol Caroline Devred Marie-Christine Lagasquie-Schiex Handling Ignorance in Argumentation: Semantics of Partial Argumentation Frameworks. 259-270 2007 conf/ecsqaru/2007 ECSQARU http://dx.doi.org/10.1007/978-3-540-75256-1_25 db/conf/ecsqaru/ecsqaru2007.html#CayrolDL07