document: Max and min limiters If A contained in omega , n > or = 2 , and the function max -LRB- -LCB- x/sub 1 / , ... , x/sub n / -RCB- intersection A -RRB- is partial recursive , it is easily seen that A is recursive . In this paper , we weaken this hypothesis in various ways -LRB- and similarly for `` min '' in place of `` max '' -RRB- 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
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