This paper discusses the no-cloning theorem in a logico-algebraic approach.
In this approach, an orthoalgebra is considered as a general structure for
propositions in a physical theory. We proved that an orthoalgebra admits
cloning operation if and only if it is a Boolean algebra. That is, only
classical theory admits the cloning of states. If unsharp propositions are to
be included in the theory, then a notion of effect algebra is considered. We
proved that an atomic Archimedean effect algebra admitting cloning operation is
a Boolean algebra. This paper also presents a partial result indicating a
relation between cloning on effect algebras and hidden variables.Comment: To appear in J. Math. Phy