Structural properties of oracle classes
نویسنده
چکیده
Denote by C the class of oracles relative to which P = NP (collapsing oracles), and by S the class of oracles relative to which P 6= NP (separating oracles). We present structural results on C and S. Using a diagonalization argument, we show that neither C nor S is closed under disjoint union, also known as join. We show that this implies that neither C nor S is closed under union, intersection, or symmetric difference. Consequently EL1, the first level of the extended low hierarchy, is not closed under join.
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عنوان ژورنال:
- Inf. Process. Lett.
دوره 109 شماره
صفحات -
تاریخ انتشار 2009