The taming of recurrences in computability logic through cirquent calculus, Part I

This paper constructs a cirquent calculus system and proves its soundness and completeness with respect to the semantics of computability logic (see http://www.cis.upenn.edu/~giorgi/cl.html). The logical vocabulary of the system consists of negation, parallel conjunction, parallel disjunction, branching recurrence, and branching corecurrence. The article is published in two parts, with (the present) Part I containing preliminaries and a soundness proof, and (the forthcoming) Part II containing a completeness proof