From tensor networks to Frobenius Schur indicators: some applications of state-sum models with boundaries

State-sum constructions have numerous applications in both mathematics and physics. In mathematics, they yield invariants for knots and manifolds and serve as a powerful organizing principle in representation theory. To illustrate this principle, we discuss equivariant Frobenius-Schur indicators. In the context of physics, we explain how state-sum models offer a conceptual framework for tensor network models, based on collaboration with Fuchs, Haegeman, Lootens, and Verstraete.