Continuing my quest to read AI: Modern Approach (Russell & Norvig 1995), Part IV is the section on Acting Logically. Chapter 11 starts with a planning agent, and the authors develop the partial order planner (POP) algorithm. Please note the planning agent is not a theorem prover or a problem solving agent, but a specialized agent with a directed search in a planning space. The authors continue with the STRIPS language to develop the operators for a planning agent.
Chapter 12 starts with the discussion of current planners (circa 1995) and its use in industry and governement. The planning topic continues with the hierarchical decomposition, generating the HD-POP algorithm. The authors continue with conditional effects and universal quantification, leading to the POP-DUNC algorithm. Finally actions have resource constraints such as materials, cost, and time.
Lastly, Chapter 13 begins a discussion regarding conditional or contingency planning. The algorithm for a conditional planning agent is presented as well as the algorithm for Conditional Partial Order Planner (CPOP). Next is the section on a simple replanning agent, and an algorithm for a replanning agent is presented. The algorithm for a situated planning agent is presented. In summary, planning agents need to account for real world issues such as incomplete information, execution errors, or unmet preconditions and have contingency plans, quickly replan, or adjust the plan as it monitors the situation during the execution.
AI planners have been used in industry for job scheduling and by governments for job scheduling for the Hubble Telescope by NASA as well as for space missions by the ESA. Other planners are discussed by history remarks in all three chapters.
The last two sections conclude knowledge and reasoning along with acting logically. The basis is first order logic (FOL) along with situational calculus. These topics work well with logic programming and the prolog programming language.