Abstract : We characterize the relations which are first-order definable in the model of the group of integers with the constant 1. This allows us to show that given a relation defined by a first-order formula in this model enriched with the usual ordering, it is recursively decidable whether or not it is first-order definable without the ordering.
Christian Choffrut, Achille Frigeri. Deciding whether the ordering is necessary in a Presburger formula. Discrete Mathematics and Theoretical Computer Science, DMTCS, 2010, Vol. 12 no. 1 (1), pp.20-37. ⟨10.46298/dmtcs.510⟩. ⟨hal-00990437⟩