In an unusual moment of agreement Mayor Bill de Blasio and former mayor Rudy Giuliani recently wrote a joint letter to Governor Cuomo and the state legislature urging a continuation of mayoral control of the school system. de Blasio and Giuliani have mostly had critical things to say about each other, with their joint letter a rare counterpoint to their more typical criticism. I asked Mayor de Blasio whether the letter signaled a change in their relationship or whether de Blasio’s 15 months in office has affected his view of Giuliani’s mayoralty.