Solving Problems by searching Well defined problems A probem is well defined if it is easy to automatically asses the validity (utility) of any proposed solution. (By easy is meant e.g. Polynomial time. However, to find an optimal solution may be computationally hard.) There are two important types of well defined problems: Path problems and Constraint Satisfaction Problems

Path problems A path problem may often be defines by the following information: a state space a known initial state a definition of a goal state a set of possible actions with well defined preconditions and effects a cost function of the path

Constraint Satisfaction Problems (CSP) CSP consists of a domain a set of variables a set of constraints on these variables an optimality function (optimising criterion) CSP are solved by carefully searching the search space making choices that restrain the search space as much as possible.

Problem overview Problems Well Defined Problems ( Validated in Polynomial Time) Ill-Defined Problems Path Problems Constraint Satisfaction Problems Constructive MethodsRepair Methods (Local Search) Constraint Handling Generate & Test (Logic Programming) Constrain & Generate (Constraint Logic Programming) Contraint Propagation A*