Mixed mode inferencing is provided by creating an extension to a RETE
network to handle both forward and backward chaining efficiently. The
extended RETE network is traversed from a root node through intermediate
nodes to the rules of the network. The intermediate nodes contain objects
that have values assigned by rules, and the intermediate nodes are linked
to those rules appropriately. When using the network in a backward
chaining context, rules linked to the intermediate node of interest are
checked to see if they are active and the rule is solvable. If not, the
related rules are checked. Because the system takes advantage of the
previously formed RETE network, these checks can be done at the rule
nodes without the need to retest each condition.