Coverage of Constraint Logic Programming (CLP) is extended and now introduced earlier in the book, in the Prolog part.
Most of the existing chapters on AI techniques have been systematically improved and updated
Coverage of planning methods is deepened in a new chapter that includes implementations of partial order planning and the GRAPHPLAN approach
The treatment of search methods now includes an RTA* program (real-time A* search)
The chapter on meta-pogramming (now chapter 25) is extended by abductive reasoning, query-the-user facility, and a sketch of CLP interpreter, all implemented as Prolog meta-interpreters
Programming examples are refreshed throughout the book, making them more interesting and practical. One such example introduces semantic reasoning with the well-known lexical database WordNet®.

Prolog Programming for Artificial Intelligence, 4th edition