Abstract:A greedy default logic is proposed in this paper, in which pseudo extensions is defined with aim of keeping as much information of the defaults as possible. The paper proves that a GD-extension of a default theory (T,Δ) in the greedy default logic may not be any extension of the default theory, and vice versa. An extension of the default theory may be a subset of a pseudo extension of a default theory (T,Δ) in the greedy default. Hence, the default logic, the greedy default logic and the greedier default logic are different logics.