Frank Horace Hahn FBA (26 April 1925 – 29 January 2013) was a British economist whose work focused on general equilibrium theory, monetary theory, Keynesian economics and monetarism.[1][2] A famous problem of economic theory, the conditions under which money (which is intrinsically worthless) can have a positive value in a general equilibrium, is called "Hahn's problem" after him.