•Let s ą ;.
•[Fagin’74] A class C µ STRUCT[s] is in 9 SO iff it is in NP
•
•Now let s = ;. A structure = a number
•[Fagin’74,
Jones&Selman’74] A set of numbers C µ N is in 9 SO iff it is in NE
(nondeterministic exponential time)
•
•PROVE IT. WHY THE JUMP IN COMPLEXITY ?