The article investigates the relation between three well-known hypotheses.
1) Hunion: the union of disjoint complete sets for NP is complete for NP
2) Hopps: there exist optimal propositional proof systems
3) Hcpair: there exist complete disjoint NP-pairs

The following results are obtained:
a) The hypotheses are pairwise independent ... more >>>

We investigate the computational complexity of balance problems for $\{-,\cdot\}$-circuits
computing finite sets of natural numbers. These problems naturally build on problems for integer
expressions and integer circuits studied by Stockmeyer and Meyer (1973),
McKenzie and Wagner (2007),
and Glaßer et al (2010).

Our work shows that the ... more >>>

We study the computational complexity of emptiness problems for circuits over sets of natural numbers with the operations union, intersection, complement, addition, and multiplication. For most settings of allowed operations we precisely characterize the complexity in terms of completeness for classes like NL, NP, and PSPACE. The case where intersection, ... more >>>

We study the computational complexity of constraint satisfaction problems that are based on integer expressions and algebraic circuits. On input of a finite set of variables and a finite set of constraints the question is whether the variables can be mapped onto finite subsets of natural numbers (resp., finite intervals ... more >>>