Conformal mapping of long quadrilaterals and thick doubly connected domains

In this paper we investigate theoretically an approximation technique for avoiding the crowding phenomenon in numerical conformal mapping. The method applies to conformal maps from rectangles to “long quadrilaterals,” i.e., Jordan domains bounded by two parallel straight lines and two Jordan arcs, where the two arcs are far apart. We require that these maps take the four corners of the rectangle to the four corners of the quadrilateral. Our main theorem tackles a conformal mapping problem for doubly connected domains, and we derive from this our results for quadrilaterals. As a corollary, we extend the “domain decomposition” mapping technique of Papamichael and Stylianopoulos. Similar results hold for the inverse maps, from quadrilaterals to rectangles.     

非自治集值映射的渐近性态

本文研究了非自治集值映射的渐近性态,利用非自治集值映射的上链性质,得到了在一定条件下非自治集值映射的上链吸引子的存在唯一性.     

Eigenvalues of harmonic almost submersions

Maps between Riemannian manifolds which are submersions on a dense subset, are studied by means of the eigenvalues of the pull-back of the target metrics, the first fundamental form. Expressions for the derivatives of these eigenvalues yield characterizations of harmonicity, totally geodesic maps and biconformal changes of metric preserving harmonicity. A Schwarz lemma for pseudo harmonic morphisms is proved, using the dilatation of the eigenvalues and, in dimension five, a Bochner technique method, involving the Laplacian of the difference of the eigenvalues, gives conditions forcing pseudo harmonic morphisms to be harmonic morphisms.     

Bands,tangles and linear skein theory

The process of attaching bands to links (fusion/fission) is discussed in the framework of tangle theory and linear skein theory. Formulas for skein polynomials are deduced and nontriviality results for band constructions are proved. In particular we discuss the effect of band changes like twisting. We prove that for each link and choice of two attaching arcs there are infinitely many different fusion/fission links with bands attached to these arcs. partially supported by NATO via DAAD     

The Area Derivative of a Space-Filling Diagram

The motion of a biomolecule greatly depends on the engulfing solution, which is mostly water. Instead of representing individual water molecules, it is desirable to develop implicit solvent models that nevertheless accurately represent the contribution of the solvent interaction to the motion. In such models, hydrophobicity is expressed as a weighted sum of atomic surface areas. The derivatives of these weighted areas contribute to the force that drives the motion. In this paper we give formulas for the weighted and unweighted area derivatives of a molecule modeled as a space-filling diagram made up of balls in motion. Other than the radii and the centers of the balls, the formulas are given in terms of the sizes of circular arcs of the boundary and edges of the power diagram. We also give inclusion–exclusion formulas for these sizes.     

A branch and bound algorithm for minimizing the number of crossing arcs in bipartite graphs

Acyclic directed graphs are widely used in many fields of economic and social sciences. This has generated considerable interest in algorithms for drawing “good” maps of acyclic diagraphs. The most important criterion to obtain a readable map of an acyclic graph is that of minimizing the number of crossing arcs. In this paper, we present a branch and bound algorithm for solving the problem of minimizing the number of crossing arcs in a bipartite graph. Computational results are reported on a set of randomly generated test problems.     

Sensitivity analysis in vector optimization

For a vector optimization problem that depends on a parameter vector, the sensitivity analysis of perturbation, proper perturbation, and weak perturbation maps is dealth with. Each of the perturbation maps is defined as a set-valued map which associates to each parameter value the set of all minimal, properly minimal, and weakly minimal points of the perturbed feasible set in the objective space with respect to a fixed ordering cone. Using contingent cones in a finite-dimensional Euclidean space, we investigate the relationship between the contingent derivatives of the three types of perturbation maps and three types of minimal point sets for the contingent derivative of the feasible-set map in the objective space. These results provide quantitative informations on the behavior of the perturbation maps.The authors would like to thank the referees for their valuable comments and suggestions.     

Computing transitive closure of bipolar weighted digraphs

We define a bipolar weighted digraph as a weighted digraph together with the sign function on the arcs such that the weight of each arc lies between 0 and 1, and no two parallel arcs have the same sign. Bipolar weighted digraphs are utilized to model so-called fuzzy cognitive maps, which are used in science, engineering, and the social sciences to represent the causal structure of a body of knowledge. It has been noted in the literature that a transitive closure of a bipolar weighted digraph contains useful new information for the fuzzy cognitive map it models.In this paper we ask two questions: what is a sensible and useful definition of transitive closure of a bipolar weighted digraph, and how do we compute it? We give two answers to each of these questions, that is, we present two distinct models. First, we give a review of the fuzzy digraph model, which has been, in a different form and less rigorously, studied previously in the fuzzy systems literature. Second, we carefully develop a probabilistic model, which is related to the notion of network reliability.This paper is intended for a mathematical audience.     

Inverse limits of arcs and of simple closed curves with confluent bonding mappings

It is proved that Knaster's type continua and solenoids can be considered as inverse limits of arcs and of circles with confluent bonding mappings. Several other classes of bonding mappings, which are relative to confluent ones, also are discussed.     

含有两个非临界点的强连通定向图的弧数

证明顶点数为$n\geq 4$,弧数为$m\geq {n-1 \choose 2}+3$的强连通定向
图$D$中存在两点$u^*$、!$v^*$,使得$D-u^*$和$D-v^*$都是强连通的, 并用例子说明这里所给的
关于弧数的下界是紧的.     

Sensitivity and stability for the second-order contingent derivative of the proper perturbation map in vector optimization

Sensitivity analysis and stability analysis in vector optimization are dealt with in this paper. First, some relationships between the second-order contingent derivative of a set-valued map and its profile map are obtained. Secondly, the upper semicontinuity and lower semicontinuity of second-order contingent derivatives of set-valued maps are established. Finally, by virtue of the second-order contingent derivative of set-valued maps, quantitative information and qualitative information on the behavior of the proper perturbation map are obtained.     

Boundary arcs for a class of differential games

The behavior of boundary arcs of the attainable set is discussed for a class of differential games, and first-order necessary conditions are obtained. The method is a simple extension of that used by Hestenes (Ref. 1) in relating the behavior of boundary arcs for optimal control problems to the maximum principle.Portions of this work were sponsored by the Douglas Aircraft Company, Independent Research and Development Fund No. 80421-021/39051.     

Epidifferentiability of the map of infima in Hilbert spaces

This article deals with derivatives for set-valued maps that take values in ordered vector spaces, in particular it concerns about the relationship between the epiderivatives of a set-valued map and its associated map of infima. When the image space is a real separable Hilbert space ordered by an orthonormal basis, by using a variational technique based on a decoupling of the ordering cone into half-spaces, we show that both epiderivatives coincide under certain hypothesis of compactness and stability. Furthermore we obtain some computation formulas for these derivatives in terms of associated scalar set-valued maps.     

Benson真有效意义下向量集值优化的广义Fritz-John条件

借助Clarke切锥并用上图引入了关于集值映射的Clarke切导数.借助于一种新的择一性定理建立了向量集值优化问题在弱Benson真有效意义下的广义Fritz-John最优性条件,而且证明在一种伪凸的假设下,这种最优性条件还为充分的.     

广义近似空间的粗糙同胚与拓扑同胚

对广义近似空间之间的映射引入并刻画了粗糙连续性和拓扑连续性,探讨了他们的性质及相互关系.证明了两个粗糙连续映射的复合还是粗糙连续的,每个粗糙连续的映射都是拓扑连续的.在此基础上引入了粗糙同胚性质和拓扑同胚性质的概念,证明了拓扑同胚性质均为粗糙同胚性质并考察了广义近似空间的诸如分离性、连通性、紧性等的粗糙同胚不变性和拓扑同胚不变性.     

Cognitive maps and fuzzy implications

A cognitive map is a collection of nodes linked by some arcs. Up to this point, there is unanimity in the literature about the previous definition. But if we look closer at the meaning of the nodes and links, we can see that there are crucial differences between the various authors. And these differences are not always explicit. In spite of this, it seems that many authors perform on the maps the same kind of analysis (strongly inspired by the book of Axelrod), even if these analyses are not consistent with their conception of a cognitive map. That is why it is important to clearly and formally define the kind of map used. In this paper, we propose a formal definition of a cognitive map relying on the concept of fuzzy implication. Thus in our framework, a node is a logical proposition and a link is an implication. Starting from our definition, we show some properties of this kind of maps and some analysis techniques.     

Analytic invariant manifolds for sequences of diffeomorphisms

We obtain real analytic invariant manifolds for trajectories of maps assuming only the existence of a nonuniform exponential behavior. We also consider the more general case of sequences of maps, which corresponds to a nonautonomous dynamics with discrete time. We emphasize that the maps that we consider are defined in a real Euclidean space, and thus, one is not able to obtain the invariant manifolds from a corresponding procedure to that in the nonuniform hyperbolicity theory in the context of holomorphic dynamics. We establish the existence both of stable (and unstable) manifolds and of center manifolds. As a byproduct of our approach we obtain an exponential control not only for the trajectories on the invariant manifolds, but also for all their derivatives.     

A class of universal approximators of real continuous functions revisited

We revisit the theorem stating that it is possible to approximate with any accuracy any real continuous function with a class of relational maps. In other words, relational maps are universal approximators. We review the key works that have proved this property, highlighting their limitations and providing yet another proof that it is not restricted by certain assumptions considered in early proofs. We also show how one can go inversely to approximate these systems with a series of polynomials. This provides us with analytical expressions of these maps which can facilitate a series of important analysis tasks such as modeling and numerical analysis of ill-defined-uncertain complex systems.

     

Existence and uniqueness of rectilinear slit maps

We consider a generalization of the parallel slit uniformization in which the angle of inclination of each image slit is assigned independently. Koebe proved that for domains of finite connectivity there is, up to a normalization, a unique rectilinear slit map achieving any given angle assignment. Koebe's theorem is partially extended to domains of infinite connectivity. A uniqueness result is shown for domains of countable connectivity and arbitrary angle assignments, and an existence result is proved for arbitrary domains under the assumption that the angle assignment is continuous and has finite range. In order to prove the existence result a new extremal length tool, called the crossing-module, is introduced. The crossing-module allows greater freedom in the family of admissible arcs than the classical module. Several results known for the module are extended to the crossing-module. A generalization of Jenkins' module condition for the parallel slit problem is given for the rectilinear slit problem in terms of the crossing-module and it is shown that rectilinear slit maps satisfying this crossing-module condition exist.

     

Measuring Differences Between Cognitive Maps

A causal cognitive map is a directed network representation of an individual's beliefs concerning a particular domain at a point of time. The nodes and the arcs joining them indicate causal beliefs. There have been few attempts to develop quantitative measures for such maps. The measures could be used to compare the maps of different individuals and also to track the changes in the beliefs of a single individual over time. They would assist in providing a more objective basis for qualitative analysis. In this paper we review current cognitive mapping research and then propose some measures for computing the difference between two maps, illustrating this work with a managerial example.