Search results for "Constraint"
showing 10 items of 361 documents
New Geometric Constraint Solving Formulation: Application to the 3D Pentahedron
2014
Geometric Constraint Solving Problems (GCSP) are nowadays routinely investigated in geometric modeling. The 3D Pentahedron problem is a GCSP defined by the lengths of its edges and the planarity of its quadrilateral faces, yielding to an under-constrained system of twelve equations in eighteen unknowns. In this work, we focus on solving the 3D Pentahedron problem in a more robust and efficient way, through a new formulation that reduces the underlying algebraic formulation to a well-constrained system of three equations in three unknowns, and avoids at the same time the use of placement rules that resolve the under-constrained original formulation. We show that geometric constraints can be …
Solution isolation strategies for the Bernstein polytopes-based solver
2013
The Bernstein polytopes-based solver is a new method developed to solve systems of nonlinear equations, which often occur in Geometric Constraint Solving Problems. The principle of this solver is to linearize nonlinear monomials and then to solve the resulting linear programming problems, through linear programming. However, without any strategy for the isolation of the many solutions of multiple-solution systems, this solver is slow in practice. To overcome this problem, we propose in this work, a study of several strategies for solution isolation, through the split of solution boxes into several subboxes, according to three main steps answering the questions: when, where, and how to perfo…
Unitarity constraint for threshold coherent pion photoproduction on the deuteron
1997
The contribution of the two-step process {gamma}d{r_arrow}pn{r_arrow}{pi}{sup 0}d to the imaginary part of the amplitude for coherent pion production on the deuteron is calculated at threshold exploiting unitarity constraints. The result shows that this absorptive process is not negligible and has to be considered in an extraction of the elementary neutron production amplitude from the {gamma}d{r_arrow}{pi}{sup 0}d cross section at threshold. {copyright} {ital 1997} {ital The American Physical Society}
An Operator Splitting Method for Pricing American Options
2008
Pricing American options using partial (integro-)differential equation based methods leads to linear complementarity problems (LCPs). The numerical solution of these problems resulting from the Black-Scholes model, Kou’s jump-diffusion model, and Heston’s stochastic volatility model are considered. The finite difference discretization is described. The solutions of the discrete LCPs are approximated using an operator splitting method which separates the linear problem and the early exercise constraint to two fractional steps. The numerical experiments demonstrate that the prices of options can be computed in a few milliseconds on a PC.
Models and Phenomena: Bas van Fraassen’s Empiricist Structuralism
2013
Bas van Fraassen’s recent endorsement of empiricist structuralism is based on a particular approach to representation. He sharply distinguishes between what makes a scientific model M a successful representation of its target T from what makes M a representation of T and not of some other different target T’. van Fraassen maintains that embedment (i.e.: a particular sort of isomorphism which relates structures) gives the answer to the first question while the user’s decision to employ model M to represent T accounts for the representational link. After discussing the rationale for this approach, I defend that indexical constraints like those favoured by van Fraassen cannot be the last word …
High Precision Astrometry Over Large Angular Scales with Closure Constraints: The Triplet 1803+784/1928+738/2007+777
1996
The technique of differential astrometry using the phase-delay VLBI observable promises fractional precisions of ~2 × 10−9 in the determination of the separation of sources 5° or 6° apart on the sky (Guirado et al. 1995a; Lara et al. 1996). In our present research we seek further improvement in this technique through using triplets of radio sources, which provide a closure constraint in the determination of relative angular positions. This constraint not only eases the resolution of the phase-cycle ambiguities (a major problem in the least-squares approach to astrometry with phase delays), but it also strongly constrains the space of allowable parameter values.
Density as a constraint and the separation of internal excitation energy in TDHF
1985
We present a fast and efficient constrained Hartree-Fock iteration scheme which constraints the complete density distribution to remain constant. The scheme is particularly suited to a coordinate- or momentum-space representation. The technique is applied to separate the collective and the internal energy in a propagating TDHF state. We study the behavior of these two energies in an16O+16O collision.
Random Variables Recorded Under Mutually Exclusive Conditions: Contextuality-by-Default
2014
We present general principles underlying analysis of the dependence of random variables (outputs) on deterministic conditions (inputs). Random outputs recorded under mutually exclusive input values are labeled by these values and considered stochastically unrelated, possessing no joint distribution. An input that does not directly influence an output creates a context for the latter. Any constraint imposed on the dependence of random outputs on inputs can be characterized by considering all possible couplings (joint distributions) imposed on stochastically unrelated outputs. The target application of these principles is a quantum mechanical system of entangled particles, with directions of …
Editorial message
2006
Geometric Computing and Reasoning (GCR) is a new track of SAC and it is dedicated to the recent trends in the domain of geometric constraint solving and automated, or computer aided, deduction in geometry.
A Learning-Automata Based Solution for Non-equal Partitioning: Partitions with Common GCD Sizes
2021
The Object Migration Automata (OMA) has been used as a powerful tool to resolve real-life partitioning problems in random Environments. The virgin OMA has also been enhanced by incorporating the latest strategies in Learning Automata (LA), namely the Pursuit and Transitivity phenomena. However, the single major handicap that it possesses is the fact that the number of objects in each partition must be equal. Obviously, one does not always encounter problems with equally-sized groups (When the true underlying problem has non-equally-sized groups, the OMA reports the best equally-sized solution as the recommended partition.). This paper is the pioneering attempt to relax this constraint. It p…