) A phone company divides a city into n cells c1 ,c2 , ...,cn . In each cell it has a tower. When a call comes to a mobile user the company has a set of probabilities p1 , p2 , ..., pn such that the user is now at cell ci with pi probability. The company wants to activate as few towers as possible on average to find the user. When it activates a tower in a cell where the user is, the search stops. Search time is divided into d slots. By the end of d slots the user must be found. The question the company faces is what are the towers(cells) to activate in slot 1, 2, ..., d as to minimize the expected number of activations. More specifically, the company wants a policy which is a collection of d sets S1 , S2 , ..., Sd where Si contains towers (cells) to be activated at slot i.