  We prove the weak-strong uniqueness for measure-valued solutions of the
incompressible Euler equations. These were introduced by R.DiPerna and A.Majda,
and in particular global existence to any L2 initial data was proven. Whether
measure-valued solutions agree with classical solutions if the latter exist has
apparently remained open. We also show that DiPerna's measure-valued solutions
to systems of conservation laws have the weak-strong uniqueness property.
