On Hamming Distances of (α+uβ)-Constacyclic Codes of Length 4p^s over F_(p^m )+uF_(p^m )

In this paper, we discuss all the Hamming distances of (α+uβ)-constacyclic codes of 4p^s length over the finite chain ring R=F_(p^m )+uF_(p^m ) with u^2=0. Using the structures of (α+uβ)-constacyclic codes of length 4p^s over R, the Hamming distances of all constacyclic codes of length 4p^s over R are determined. We provide some parameters of good codes over R as examples, from which some are new in literature.