__T(X__

**The Formulation of the backtracking :**_{1},X

_{2},...,X

_{i}): set of all possible values for x

_{i+1}such that (X

_{1},X

_{2},...,X

_{i},X

_{i+1}) is also a B

_{i+1>}(X

_{1},X

_{2},...,X

_{i},X

_{i+1}): bounding function If B

_{i+1>}(X

_{1},X

_{2},...,X

_{i},X

_{i+1}) is false, then the path cannot be extended to reach an answer node.