... Hindawi Publishing CorporationAdvances in Difference EquationsVolume 2009, Article ID 603271, 10 pagesdoi:10.1155/2009/603271 Research Article Impulsive Periodic Boundary Value Problems ... t±iyt, and ytiyt−i. Define 0,T{t ∈ T :0≤ t ≤ T} and note thatthe intervals a, b, a, b, and a, b are defined similarly.Advances in Difference Equations 5Apply the periodic boundary ... Introduction with Applications,Birkh¨auser, Boston, Mass, USA, 2001.21 M. Bohner and A. Peterson, Advances in Dynamic Equations on Time Scales,Birkh¨auser, Boston, Mass,USA, 2003.22 D. R. Smart,...