  The dynamics of belief and knowledge is one of the major components of any
autonomous system that should be able to incorporate new pieces of information.
We introduced the Horn knowledge base dynamics to deal with two important
points: first, to handle belief states that need not be deductively closed; and
the second point is the ability to declare certain parts of the belief as
immutable. In this paper, we address another, radically new approach to this
problem. This approach is very close to the Hansson's dyadic representation of
belief. Here, we consider the immutable part as defining a new logical system.
By a logical system, we mean that it defines its own consequence relation and
closure operator. Based on this, we provide an abductive framework for Horn
knowledge base dynamics.
