If OPS-5 were actually to compute the conflict set (all rules that can be satisfied by all data in all combinations), the computational load would be enormous. Instead, OPS-5 computes the ``derivative'' of the conflict set, i.e., those rules newly enabled as a result of the changes made by the last rule, using the RETE algorithm[C. Forgy, ``Rete: A Fast Algorithm for the Many Pattern / Many Object Pattern Match Problem'', Artificial Intelligence, vol. 19, no. 1 (sept. 1982), pp. 17-38. D. Miranker has an alternative algorithm called TREAT.]

Conflict Resolution Algorithm:

1. A rule instantiation can only fire once (prevents loops).
2. Rules whose left-hand side involves the data most recently added to working memory are favored (gives search a ``depth-first'' bias).
3. Rules with a more specific left-hand side (i.e., more clauses on the left-hand side) are favored.

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