Minimizing restricted-fanout queries

Conjunctive queries form an important subset of relational algebra. Each conjunctive query has a unique minimum equivalent (up to isomorphism). However, the computation of the minimum equivalent is complete for co-NP. Johnson and Klug have proposed a subclass of conjunctive queries, the fanout-free queries, for which minimization may be performed in polynomial time. In this paper, we show that a strict superclass of the fanout-free queries, the restricted-fanout queries, can be minimized in polynomial time.