Feature-based diversity optimization for problem instance classification

Parallel Problem Solving from Nature – PPSN XIVUnderstanding the behaviour of heuristic search methods is a challenge. This even holds for simple local search methods such as 2-OPT for the Traveling Salesperson problem. In this paper, we present a general framework that is able to construct a diverse set of instances that are hard or easy for a given search heuristic. Such a diverse set is obtained by using an evolutionary algorithm for constructing hard or easy instances that are diverse with respect to different features of the underlying problem. Examining the constructed instance sets, we show that many combinations of two or three features give a good classification of the TSP instances in terms of whether they are hard to be solved by 2-OPT.Wanru Gao, Samadhi Nallaperuma, and Frank Neuman

Genomic Analysis of the Hydrocarbon-Producing, Cellulolytic, Endophytic Fungus Ascocoryne sarcoides

The microbial conversion of solid cellulosic biomass to liquid biofuels may provide a renewable energy source for transportation fuels. Endophytes represent a promising group of organisms, as they are a mostly untapped reservoir of metabolic diversity. They are often able to degrade cellulose, and they can produce an extraordinary diversity of metabolites. The filamentous fungal endophyte Ascocoryne sarcoides was shown to produce potential-biofuel metabolites when grown on a cellulose-based medium; however, the genetic pathways needed for this production are unknown and the lack of genetic tools makes traditional reverse genetics difficult. We present the genomic characterization of A. sarcoides and use transcriptomic and metabolomic data to describe the genes involved in cellulose degradation and to provide hypotheses for the biofuel production pathways. In total, almost 80 biosynthetic clusters were identified, including several previously found only in plants. Additionally, many transcriptionally active regions outside of genes showed condition-specific expression, offering more evidence for the role of long non-coding RNA in gene regulation. This is one of the highest quality fungal genomes and, to our knowledge, the only thoroughly annotated and transcriptionally profiled fungal endophyte genome currently available. The analyses and datasets contribute to the study of cellulose degradation and biofuel production and provide the genomic foundation for the study of a model endophyte system

In search of income reference points for SLCA using a country level sustainability benchmark (part 1): fair inequality. A contribution to the Oiconomy project

Purpose: This paper is part 1 of our twin articles on income reference points for Social Life Cycle Assessment (SLCA). Preventative costs based LCA systems, such as the EcoCost system and the Oiconomy system, need targets (performance reference points) to determine the marginal preventative costs, the costs of the most expensive measure that globally needs to be employed to reach the target. To extend the EcoCost system for social issues, targets are required for issues like fair wages and fair inequality of wages, issues for which no agreed standard, no effect level or target exists. One way of setting targets is to take best practices as benchmark, e.g. the practices of a group of best performing countries. The purpose of this part 1 article is to first develop a well-founded benchmark group of the 20 % best performing countries and thereafter propose a well-founded target for the issue of inequality for preventative costs based SLCA, which can also serve as performance reference point for SLCA in general and for other uses. In part 2, for the same purposes and using the same benchmark group, we propose targets for fair minimum wages for every country. Methods: A benchmark group of countries for the setting of targets was determined by an assessment of available country performance indicators, based on 5 criteria. Thereafter, we derived a proposal for a maximum inequality ratio based on existing democratically determined inequality ratios in the benchmark group. Results and discussion: The Sustainable Society Index–Human Wellbeing proved the best indicator for a country benchmark for preventative cost-based SLCA. Using the average of maximum democratically determined income differences in a benchmark group of countries determined by this index, a performance reference point for SLCA for the issue of fair inequality was derived and proposed, resulting in a maximum ratio of income differences for governmental institutions of 14.1, for government ruled companies of 18.3 and for industry of a factor 23.8. Conclusions: It proved possible to derive a target for maximum inequality of wages, based on democratic choices in a benchmark group of the 20 % best performing countries. The target for governmental institutions may be called objective, and proposed augmentations for government ruled companies and industry, though value choices, seem reasonable for the consumer who requires prevention of all possible harm as consequence of his purchase choices and who, as a voter, contributes to governmental standards

Algorithmic Strategies for a Fast Exploration of the TSP 4-OPT Neighborhood

The 4-OPT neighborhood for the TSP contains \u398(n4) moves so that finding the best move effectively requires some ingenuity. Recently, de Berg et al. have given a \u398(n3) dynamic program, but the cubic complexity is still too large for using 4-OPT in practice. We describe a new procedure which behaves, on average, slightly worse than a quadratic algorithm. This is much faster than the DP procedure, achieving speedups of two to three orders of magnitude on all instances we tested

Fitness Landscapes And Performance Of Meta-Heuristics

We perform a statistical analysis of the structure of the search space of some planar, euclidian instances of the traveling salesman problem. We want to depict this structure from the point of view of iterated local search algorithms