Periodic boundary value problems for first-order impulsive dynamic equations on time scales

This paper deals with the periodic boundary value problem for a class of first-order impulsive dynamic equations on time scales. We introduce a new notion of lower and upper solutions, which extends the classical lower and upper solutions. The existence of extremal solutions is presented by virtue of the method of lower and upper solutions coupled with monotone iterative technique. An example is also included to illustrate the main results.