A Σ3 Boolean circuit has 3 levels of gates. The input level is comprised of OR gates each taking as inputs 2, not necessarily distinct, literals. Each of these OR’s feeds one or more AND gates at the second level. Their outputs form the inputs to a single OR gate at the output level. Using the projection technique of Paturi, Saks, and Zane, it is shown that the smallest Σ3 Boolean circuit testi...