Revisiting the thirty years-old notions of resource-bounded immunity and simplicity, we investigate the structural characteristics of various immunity notions: strong immunity, almost immunity, and hyperimmunity as well as their corresponding simplicity notions. We also study limited immunity and simplicity, called k-immunity and feasible k-immunity, and their simplicity notions. Finally, we ... more >>>

We survey results on the hardness of approximating combinatorial
optimization problems.

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In this paper we define a many-one reduction which is allowed to work in exponential time but may only output polynomially many symbols. We show that there are no NEXP-hard sparse languages under our reduction unless EXP=UEXP.

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