Search results for "BINARY"
showing 10 items of 833 documents
Structural difficulty in grammatical evolution versus genetic programming
2013
Genetic programming (GP) has problems with structural difficulty as it is unable to search effectively for solutions requiring very full or very narrow trees. As a result of structural difficulty, GP has a bias towards narrow trees which means it searches effectively for solutions requiring narrow trees. This paper focuses on the structural difficulty of grammatical evolution (GE). In contrast to GP, GE works on variable-length binary strings and uses a grammar in Backus-Naur Form (BNF) to map linear genotypes to phenotype trees. The paper studies whether and how GE is affected by structural difficulty. For the analysis, we perform random walks through the search space and compare the struc…
Efficient lower and upper bounds of the diagonal-flip distance between triangulations
2006
There remains today an open problem whether the rotation distance between binary trees or equivalently the diagonal-flip distance between triangulations can be computed in polynomial time. We present an efficient algorithm for computing lower and upper bounds of this distance between a pair of triangulations.
An efficient upper bound of the rotation distance of binary trees
2000
A polynomial time algorithm is developed for computing an upper bound for the rotation distance of binary trees and equivalently for the diagonal-flip distance of convex polygons triangulations. Ordinal tools are used.
On the Locality of Standard Search Operators in Grammatical Evolution
2014
Offspring should be similar to their parents and inherit their relevant properties. This general design principle of search operators in evolutionary algorithms is either known as locality or geometry of search operators, respectively. It takes a geometric perspective on search operators and suggests that the distance between an offspring and its parents should be less than or equal to the distance between both parents. This paper examines the locality of standard search operators used in grammatical evolution (GE) and genetic programming (GP) for binary tree problems. Both standard GE and GP search operators suffer from low locality since a substantial number of search steps result in an o…
The Myriad Virtues of Wavelet Trees
2009
Wavelet Trees have been introduced in [Grossi, Gupta and Vitter, SODA '03] and have been rapidly recognized as a very flexible tool for the design of compressed full-text indexes and data compressors. Although several papers have investigated the beauty and usefulness of this data structure in the full-text indexing scenario, its impact on data compression has not been fully explored. In this paper we provide a complete theoretical analysis of a wide class of compression algorithms based on Wavelet Trees. We also show how to improve their asymptotic performance by introducing a novel framework, called Generalized Wavelet Trees, that aims for the best combination of binary compressors (like,…
Computation of Unstable Binodals Not Requiring Concentration Derivatives of the Gibbs Energy
1998
The equilibrium of three liquid phases in a binary mixture implies the existence of tie lines and binodals that are different from the normal experimentally observable ones. First of all, there are the metastable extensions of the binodal built up by S/S tie lines. These S/S tie lines fulfill the equilibrium condition of the minimum of the Gibbs energy of the entire two-phase system. Both coexisting phases are located within the meta(stable) region. There are two additional types of tie lines: U/U (maximum of the Gibbs energy; both end points within the unstable area) and U/S tie lines (saddle point; one end point within the (meta)stable, the other within the unstable region). All types of…
Critical end point behaviour in a binary fluid mixture
1997
We consider the liquid-gas phase boundary in a binary fluid mixture near its critical end point. Using general scaling arguments we show that the diameter of the liquid-gas coexistence curve exhibits singular behaviour as the critical end point is approached. This prediction is tested by means of extensive Monte-Carlo simulations of a symmetrical Lennard-Jones binary mixture within the grand canonical ensemble. The simulation results show clear evidence for the proposed singularity, as well as confirming a previously predicted singularity in the coexistence chemical potential [Fisher and Upton, Phys. Rev. Lett. 65, 2402 (1990)]. The results suggest that the observed singularities, particula…
Sedimentation of dissolved macromolecules in the vicinity of the consolute point 1. Strictly binary systems and kinetic considerations
1986
This paper analyzes the effect of gravity on polymer solutions near the consolute point. Calculations are carried out for monodisperse polystyrene in cyclohexane using the Flory-Huggins expression with a concentration-dependent interaction parameter for the free energy of mixing. Depending on molecular weight and distance to the demixing temperature, the influence of gravity leads to non-negligible gradients of the volume fraction in the one-phase region as well as in the two-phase region. In particular, the effect of gravity on the measurement of the coexistence curve in a finite sample is calculated explicitly.
Local Directional Multi Radius Binary Pattern
2018
Face recognition becomes an important task performed routinely in our daily lives. This application is encouraged by the wide availability of powerful and low-cost desktop and embedded computing systems, while the need comes from the integration in too much real world systems including biometric authentication, surveillance, human-computer interaction, and multimedia management. This article proposes a new variant of LBP descriptor referred as Local Directional Multi Radius Binary Pattern (LDMRBP) as a robust and effective face descriptor. The proposed LDMRBP operator is built using new neighborhood topology and new pattern encoding scheme. The adopted face recognition system consists of th…
Numerical Simulations of Relativistic Wind Accretion onto Black Holes Using Godunov-Type Methods
2001
We have studied numerically the so-called Bondi-Hoyle (wind) accretion onto a rotating black hole in general relativity. We have used the Kerr-Schild form of the Kerr metric, free of coordinate singularities at the black hole horizon. The ‘test-fluid’ approximation has been adopted, assuming no dynamical evolution of the gravitational field. We have used a formulation of the relativistic hydrodynamic equations which casts them into a first-order hyperbolic system of conservation laws. Our studies were performed using a Godunov-type scheme based on Marquina’s flux-formula.