  In this paper, we introduce the Dual-minus partial order, get some
characterizations of the partial order, and prove that both the dual star
partial order and the dual sharp partial order are Dual-minus-type partial
orders. Based on the Dual-minus partial order, we introduce the Dual-minus
sharp partial order and the Dual-minus star partial order, which are also
Dual-minus-type partial orders. In addition, we discuss relationships among the
Dual-minus sharp partial order, the D-sharp partial order and the G-sharp
partial order(the Dual-minus star partial order, the D-star partial order and
the P-star partial order).
