theorem instEconomicAgentAtToParent
theorem instEconomicAgentAtToParent: ∀ (x t : Type) [EconomicAgent.At x t], MaterialEntity.At x t
theorem instEconomicAgentAtToParent
theorem instEconomicAgentAtToParent: ∀ (x t : Type) [EconomicAgent.At x t], MaterialEntity.At x t