A salesman in a red suit who looks suspiciously like Tom Waits presents you with a black steel box with n binary switches on the front and a light bulb on the top. The salesman tells you that the state of the light bulb is controlled by a complex boolean circuit—a collection of AND, OR, and NOT gates connected by wires, with one input wire for each switch and a single output wire for the light ...

A salesman in a red suit who looks suspiciously like Tom Waits presents you with a black steel box with n binary switches on the front and a light bulb on the top. The salesman tells you that the state of the light bulb is controlled by a complex boolean circuit—a collection of AND, OR, and NOT gates connected by wires, with one input wire for each switch and a single output wire for the light ...

The theory of NP-completeness, as developed by Cook, Levin, and Karp, states that any language, L in NP is reducible to the Boolean satisfiability problem, 3SAT. By this, we mean that for every instance, x of the language L, we can obtain a satisfiability instance, φ such that x ∈ L if and only if φ is satisfiable. Thus, 3SAT is at least as hard as any other problem in NP. Karp further showed t...

Strong bisimilarity of Basic Parallel Processes (BPP) is decidable, but the best known algorithm has non-elementary complexity [7]. On the other hand, no lower bound for the problem was known. We show that strong bisimilarity of BPP is co-NP-hard. Weak bisimilarity of BPP is not known to be decidable, but an NP lower bound has been shown in [31]. We improve this result by showing that weak bisi...