Quotient Space Based Problem Solving provides an in‎-depth treatment of hierarchical problem solving‎,‎ computational complexity‎,‎ and the principles and applications of multi‎-granular computing‎,‎ including inference‎,‎ information fusing‎,‎ planning‎,‎ and heuristic search‎.‎ It explains the theory of hierarchical problem solving‎,‎ its computational complexity‎,‎ and discusses the principle and applications of multi‎-granular computing‎.‎ It describes a human‎-like‎,‎ theoretical framework using quotient space theory‎,‎ that will be of interest to researchers in artificial intelligence‎.‎ It provides many applications and examples in the engineering and computer science area‎.‎ It includes complete coverage of planning‎,‎ heuristic search and coverage of strictly mathematical models‎.‎