A reusable iterative optimization software library to solve combinatorial problems with approximate reasoning

Real world combinatorial optimization problems such as scheduling are typically too complex to solve with exact methods. Additionally, the problems often have to observe vaguely specified constraints of different importance, the available data may be uncertain, and compromises between antagonistic criteria may be necessary. We present a combination of approximate reasoning based constraints and iterative optimization based heuristics that help to model and solve such problems in a framework of C++ software libraries called StarFLIP++. While initially developed to schedule continuous caster units in steel plants, we present in this paper results from reusing the library components in a shift scheduling system for the workforce of an industrial production plant.Comment: 33 pages, 9 figures; for a project overview see http://www.dbai.tuwien.ac.at/proj/StarFLIP

Doubly Charged Coronene Clusters – Much Smaller than Previously Observed

The smallest doubly charged coronene cluster ions reported so far, Cor152+, were produced by charge exchange between bare coronene clusters and He2+ [H. A. B. Johansson et al., Phys. Rev. A 84, 043201 (2011)]. These dications are at least five times larger than the estimated Rayleigh limit, i.e., the size at which the activation barrier for charge separation vanishes. Such a large discrepancy is unheard of for doubly charged atomic or molecular clusters. Here we report the mass spectrometric observation of doubly charged coronene trimers, produced by electron ionization of helium nanodroplets doped with coronene. The observation implies that Cor32+ features a non-zero fission barrier too large to overcome under the present experimental conditions. The height of the barriers for the dimer and trimer has been estimated by means of density functional theory calculations. A sizeable barrier for the trimer has been revealed in agreement with the experimental findings

Implementation of a Shift Scheduling Application using the *FLIP++ Environment

DomFLIP++ is the knowledge representation module of the FLIP++ (pronounce: StarFlipPlusPlus) project. FLIP++ is a tool that is focused on optimizing multiple criteria problems. It uses fuzzy constraints to model optimizing criteria and applies various iterative improvement techniques such as Tabu search, genetic algorithms, and iterative deepening to the problems. DomFLIP++ is implemented in the C++ programming language making intensive use of the Standard Template Library. It allows the definition of new optimization problems by aiding the domain engineer in the design of the structure of a new problem at hand. Generally, a division between domaindependent and domain-independent methods and data structures characterizes the structure of DomFLIP++. While the domain-dependent data structures are specific to the problem, the domain-independent part is provided as a framework by the library. Moreover, there is a domain-independent interface to other FLIP++ modules such as OptiFLIP++, Dyna..

FLIP++ - A fuzzy logic inference processor library

FLIP++ is a fuzzy logic inference processor library. This C++ library was developed to do calculations with uncertain data and priorities. It evaluates various types of rules of different importance from a hierarchy of rules for uncertain or precise data. It evaluates only those parts of the hierarchy needed for the result. The result itself has two forms: first as a list of membership functions, and second as a crisp value usable for fuzzy control. The library also contains the whole functionality needed to manage one or more sets of rules on all data. It is built to be easily adapted to new applications. Due to its quite general concept of the classes it is possible to include it for the purpose of fuzzy computations in other systems. Please send all correspondence regarding this paper to Wolfgang Slany. 1 FLIP++ as part of a scheduling project FLIP++ is usable as a standalone fuzzy control module together with the user interface from the InterFLIP++ library. Alternatively it ca..

Modeling constraints with the fuzzy logic inference processor FLIP++

this paper the representation of knowledge will be shown in an example that is typical for the use of the whole FLIP++ project, which FLIP++ is a part of. The example consists of constraints needed for scheduling a steelmaking plant. Here, three different types of constraints are used: first the chemical compatibility constraints, which will be shown in detail, second the temporal constraints for the representation of delivery dates that have to be fulfilled, and third the capacity constraints for human, machinery and other common restrictions. Each of these three constraints consists of many different subconstraints. The chemical compatibility constraint, for example, consists of constraints for every measured chemical element. It is derived from the difference between the contents of an element in the old and the new load. This difference in content is also a qualitative variable with terms as value to express the difference. Here we will use the percentage difference for the chemical element Nickel (Ni) as qualitative variable with the allowed terms: negative, negative small, zero, positive small and positive. Figure 1 shows the corresponding membership functions for such a representation. We will later derive from this variable the constraint for the compatibility for Ni by using rules. 2 Quantitative knowledge representatio