Logic and Computation through the Lens of Semirings

We study the expressivity and computational aspects of first-order logic and its extensions in the semiring semantics developed by Grädel and Tannen. We characterize the complexity of model checking and data complexity of first-order logic both in terms of a generalization of Blum-Shub-Smale machines and arithmetic circuits defined over a semiring. In particular, we give a logical characterization of constant-depth arithmetic circuits by an extension of first-order logic that holds for any semiring that is both commutative and positive.