The paper describes the main ideas and principles of HAP (Hybrid representation of Actions and Plans), a system for hybrid representation and reasoning in advanced robotics. In this context, hybrid representation refers to the integration of both symbolic and analogic knowledge representation paradigms. In particular, the logic/symbolic component is based on a KL-ONE-like representation language. The system embeds "analogic experts", that are concurrent procedures operating in a direct and fast way on the world representation. These "experts" help the system in planning a correct temporal sequence of actions. As a reference scenario, assembly (and disassembly) problems are considered. The assembly problem can be decomposed in several suitable concurrent sub-tasks, which involves both robotic aspects as navigation, obstacle avoidance, grasping, and AI aspects as action planning and world representation. As a case study, the paper discusses the assembly of a complex object from parts as an experimental paradigm for planning movements of a redundant robot in an unstructured environment.