title: Max and min limiters
abstract: If A contained in omega , n>or=2, and the function max({x/sub 1/,...,x/sub n/} intersection A) is partial recursive, it is easily seen that A is recursive. In this paper, we weaken this hypothesis in various ways (and similarly for "min" in place of "max") and investigate what effect this has on the complexity of A. We discover a sharp contrast between retraceable and co-retraceable sets, and we characterize sets which are the union of a recursive set and a co-r.e., retraceable set. Most of our proofs are noneffective. Several open questions are raised
keyphrases: min limiters complexity retraceable sets recursive set max limiters