Explore the fourth lecture in a series on diagrammatic categories in algebra presented by Emily Peters. Delve into a specific example of diagrammatic categories and its unique formalism as part of the Workshop on Quantum symmetries: Tensor Categories, Topological quantum field theories, and Vertex algebras. Gain insights into how these diagrammatic representations emerge across various subfields of algebra. Engage with the material and consider potential generalizations of the concepts presented. This 52-minute talk, hosted by the Centre de recherches mathématiques (CRM), offers an in-depth look at an important topic in modern algebraic theory.