CSM-365 - Using schema theory to explore interactions of multiple operators

In the last two years the schema theory for Genetic Programming (GP) has been applied to the problem of understanding the length biases of a variety of crossover and mutation operators on variable length linear structures. In these initial papers, operators were studied in isolation. In practice, however, they are typically used in various combinations, and in this paper we present the first schema theory analysis of the complex interactions of multiple operators. In particular we apply the schema theory to the use of standard subtree crossover, full mutation, and grow mutation (in varying proportions) to variable length linear structures in the one-then-zeros problem. We then show how the results can be used to guide choices about the relative proportion of these operators in order to achieve certain structural goals during a run

Harvesting Entities from the Web Using Unique Identifiers -- IBEX

In this paper we study the prevalence of unique entity identifiers on the Web. These are, e.g., ISBNs (for books), GTINs (for commercial products), DOIs (for documents), email addresses, and others. We show how these identifiers can be harvested systematically from Web pages, and how they can be associated with human-readable names for the entities at large scale. Starting with a simple extraction of identifiers and names from Web pages, we show how we can use the properties of unique identifiers to filter out noise and clean up the extraction result on the entire corpus. The end result is a database of millions of uniquely identified entities of different types, with an accuracy of 73--96% and a very high coverage compared to existing knowledge bases. We use this database to compute novel statistics on the presence of products, people, and other entities on the Web.Comment: 30 pages, 5 figures, 9 tables. Complete technical report for A. Talaika, J. A. Biega, A. Amarilli, and F. M. Suchanek. IBEX: Harvesting Entities from the Web Using Unique Identifiers. WebDB workshop, 201

Dynamical Interactions and the Black Hole Merger Rate of the Universe

Binary black holes can form efficiently in dense young stellar clusters, such as the progenitors of globular clusters, via a combination of gravitational segregation and cluster evaporation. We use simple analytic arguments supported by detailed N-body simulations to determine how frequently black holes born in a single stellar cluster should form binaries, be ejected from the cluster, and merge through the emission of gravitational radiation. We then convolve this ``transfer function'' relating cluster formation to black hole mergers with (i) the distribution of observed cluster masses and (ii) the star formation history of the universe, assuming that a significant fraction gcl of star formation occurs in clusters and that a significant fraction gcand of clusters undergo this segregation and evaporation process. We predict future ground--based gravitational wave (GW) detectors could observe ~500 (gcl/0.5) (gcand/0.1) double black hole mergers per year, and the presently operating LIGO interferometer would have a chance (50%) at detecting a merger during its first full year of science data. More realistically, advanced LIGO and similar next-generation gravitational wave observatories provide unique opportunities to constrain otherwise inaccessible properties of clusters formed in the early universe.Comment: 4 pages, 2 figures. To appear in PRD Rapid Communication

On Convergence of the Inexact Rayleigh Quotient Iteration with the Lanczos Method Used for Solving Linear Systems

For the Hermitian inexact Rayleigh quotient iteration (RQI), the author has established new local general convergence results, independent of iterative solvers for inner linear systems. The theory shows that the method locally converges quadratically under a new condition, called the uniform positiveness condition. In this paper we first consider the local convergence of the inexact RQI with the unpreconditioned Lanczos method for the linear systems. Some attractive properties are derived for the residuals, whose norms are $\xi_{k+1}$'s, of the linear systems obtained by the Lanczos method. Based on them and the new general convergence results, we make a refined analysis and establish new local convergence results. It is proved that the inexact RQI with Lanczos converges quadratically provided that $\xi_{k+1}\leq\xi$ with a constant $\xi\geq 1$. The method is guaranteed to converge linearly provided that $\xi_{k+1}$ is bounded by a small multiple of the reciprocal of the residual norm $\|r_k\|$ of the current approximate eigenpair. The results are fundamentally different from the existing convergence results that always require $\xi_{k+1}<1$, and they have a strong impact on effective implementations of the method. We extend the new theory to the inexact RQI with a tuned preconditioned Lanczos for the linear systems. Based on the new theory, we can design practical criteria to control $\xi_{k+1}$ to achieve quadratic convergence and implement the method more effectively than ever before. Numerical experiments confirm our theory.Comment: 20 pages, 8 figures. arXiv admin note: text overlap with arXiv:0906.223

Early growth of field-grown swiss flint maize landraces

Mild cold stress (chilling) limits early growth of maize (Zea mays L.) in central and northern Europe. Introgression of chilling tolerance from landraces has been proposed, because the genetic basis for chilling tolerance of European Flint x Dent hybrids is small. Therefore, the aim of this study was a detailed characterization of the chilling toler¬ance of Swiss maize landraces, hypothesizing a relatively good performance in marginal thermal environments. The environments were set up by different sowing dates in two years. A functional growth analysis of the shoot from the one-leaf to the six-leaf stage was conducted with eight Swiss landraces and a check hybrid (Magister). The mean air temperature calculated across the six environments was above 15°C. Under these conditions, none of the landraces grew consistently better than Magister. Some landrace-specific relative growth reactions were observed compared to Magister, apparently due to strong changes in the temperature course. However, based on this study direct use of Swiss maize landraces in breeding for the improvement of chilling tolerance is not recom¬mended. More detailed investigations of promising landraces are proposed

Early growth of field-grown swiss flint maize landraces

Mild cold stress (chilling) limits early growth of maize (Zea mays L.) in central and northern Europe. Introgression of chilling tolerance from landraces has been proposed, because the genetic basis for chilling tolerance of European Flint x Dent hybrids is small. Therefore, the aim of this study was a detailed characterization of the chilling toler¬ance of Swiss maize landraces, hypothesizing a relatively good performance in marginal thermal environments. The environments were set up by different sowing dates in two years. A functional growth analysis of the shoot from the one-leaf to the six-leaf stage was conducted with eight Swiss landraces and a check hybrid (Magister). The mean air temperature calculated across the six environments was above 15°C. Under these conditions, none of the landraces grew consistently better than Magister. Some landrace-specific relative growth reactions were observed compared to Magister, apparently due to strong changes in the temperature course. However, based on this study direct use of Swiss maize landraces in breeding for the improvement of chilling tolerance is not recom¬mended. More detailed investigations of promising landraces are proposed