2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/156180Bellantoni and Cook have given a function-algebra characterization of the polynomial-time computable functions via an unbounded recursion scheme which is called safe recursion. Inspired by their work, we characterize the exponential-time computable functions with the use of a safe variant of nested recursion.Computational ComplexityF.4.1; F.1.1; F.1.3text