1) The document discusses multiple representations in artificial cognitive systems, including both external representations like diagrams and internal mental representations like visual mental imagery. 2) It presents examples of how problems can be solved using either a mathematical/propositional representation or a visual/imagery-based representation. 3) Leading cognitive architectures are discussed in terms of how they have begun to incorporate multiple representations, with some exploring non-symbolic, array-based representations to model processes involved in visual mental imagery.