TY - GEN A1 - Meer, Klaus A1 - Weber, Gerhard Wilhelm T1 - Some aspects of studying an optimization or decision problem in different computational models T2 - European Journal of Operational Research N2 - In this paper we want to discuss some of the features coming up when analyzing a problem in different complexity theoretic frameworks. The focus will be on two problems. The first is related to mathematical optimization. We consider the quadratic programming problem of minimizing a quadratic polynomial on a polyhedron. We discuss how the complexity of this problem might change if we consider real data together with an algebraic model of computation (the Blum–Shub–Smale model) instead of rational inputs together with the Turing machine model. The results obtained will lead us to the second problem; it deals with the intrinsic structure of complexity classes in models over real- or algebraically closed fields. A classical theorem by Ladner for the Turing model is examined in these different frameworks. Both examples serve well for working out in how far different approaches to the same problem might shed light upon each other. In some cases this will lead to quite diverse results with respect to the different models. On the other hand, for some problems the more general approach can also give a unifying idea why results hold true in several frameworks. The paper is of tutorial character in that it collects some results into the above direction obtained previously. KW - Complexity theory Saturation KW - Algebraic models of computation KW - Linear and quadratic programming KW - Structure of complexity classes Y1 - 2002 UR - http://www.sciencedirect.com/science/article/pii/S0377221702002692 U6 - https://doi.org/10.1016/S0377-2217(02)00269-2 SN - 0377-2217 VL - 143 IS - 2 SP - 406 EP - 418 ER - TY - GEN A1 - Defterli, Özlem A1 - Fügenschuh, Armin A1 - Weber, Gerhard Wilhelm T1 - Modern Tools for the Time-Discrete Dynamics and Optimization of Gene- Environment Networks T2 - Communications in Nonlinear Science and Numerical Simulation Y1 - 2011 U6 - https://doi.org/10.1016/j.cnsns.2011.03.003 SN - 1007-5704 VL - 16 IS - 12 SP - 4768 EP - 4779 ER -