bluuebunny/crossref_metadata_2025 huggingface dataset:
EXISTENCE AND REGULARITY RESULTS FOR THE STOKES SYSTEM WITH NON-SMOOTH BOUNDARY DATA IN A POLYGON
Authors: MOUSSAOUI M. , ZINE A. M.
Published: May 2003

We discuss the problem of existence and uniqueness of solutions for the nonhomogeneous Stokes system in a plane polygon with non-smooth boundary data.
NUMERICAL STUDY OF ELLIPTIC-HYPERBOLIC DAVEY–STEWARTSON SYSTEM: DROMIONS SIMULATION AND BLOW-UP
Authors: BESSE C. , BRUNEAU C. H.
Published: May 2003

This paper is devoted to the numerical approximation of the elliptic-hyperbolic form of the Davey–Stewartson equations. A well-suited finite differences scheme that preserves the energy is derived. This scheme is tested to compute the famous dromion 1–1 and dromion 2–2 solutions. The accuracy of Crank–Nicolson scheme is discussed and it is shown that it induces a phase error. The qualitative behaviour of the solutions is then studied; in particular the influence of the initial datum and of the various parameters is pointed out. Finally, numerical experiments show the existence of blow-up solutions.
A DOMAIN DECOMPOSITION METHOD FOR A BONDED STRUCTURE
Authors: GEYMONAT G. , KRASUCKI F. , MARINI D. , VIDRASCU M.
Published: May 2003

We show that the transmission conditions through two elastic bodies bonded by a thin adhesive layer can be written as Robin-type conditions, well-suited for using a domain decomposition algorithm for which we prove convergence. Numerical approximation by means of finite element methods is also presented and analyzed. Convergence of the discrete algorithm is proven as well as optimal error estimates.
BRAIDED CHORD DIAGRAMS
Authors: Birman Joan S. , Trapp Rolland
Published: May 2003

The notion of a braided chord diagram is introduced and studied. An equivalence relation is given which identifies all braidings of a fixed chord diagram. It is shown that finite-type invariants are stratified by braid index for knots which can be represented as closed 3-braids. Partial results are obtained about spanning sets for the algebra of chord diagrams of braid index 3.
A PROOF OF THE MELVIN–MORTON CONJECTURE AND FEYNMAN DIAGRAMS
Authors: CHMUTOV S.
Published: May 2003

The Melvin–Morton conjecture says how the Alexander–Conway knot invariant function can be read from the coloured Jones function. It has been proved by D. Bar-Natan and S. Garoufalidis. They reduced the conjecture to a statement about weight systems. The proof of the latter is the most difficult part of their paper. We give a new proof of the statement based on the Feynman diagram description of the primitive space of the Hopf algebra [Formula: see text] of chord diagrams.
FLOER HOMOLOGY OF TOPOLOGICAL IMITATIONS OF HOMOLOGY 3-SPHERES
Authors: KAWAUCHI AKIO
Published: May 2003

We introduce the notion of weak slice for a homology 3-sphere or a knot in it in order to compute the Floer homology of topological imitations of a given homology 3-sphere. We obtain a qualitative result on the Floer homology. In particular, infinitely many hyperbolic homology 3-spheres with the same Floer homology are constructed as topological imitations of every given homology 3-sphere. The well-known connected sum and periodicity questions on the Floer homology are also discussed.
Weight Systems from Feynman Diagrams
Authors: Kreimer Dirk
Published: May 2003

We find that the overall UV divergences of a renormalizable field theory with trivalent vertices fulfil a four-term relation. They thus come close to establish a weight system. This provides a first explanation of the recent successful association of renormalization theory with knot theory.
AMPHICHEIRAL LINKS WITH ODD CROSSING NUMBER
Authors: LIANG CHENGZHI , MISLOW KURT , FLAPAN ERICA
Published: May 2003

We give two examples of amphicheiral links with odd crossing numbers; one of an unoriented amphicheiral link and the other of an oriented amphicheiral link.
ENUMERATION OF CHORD DIAGRAMS AND AN UPPER BOUND FOR VASSILIEV INVARIANTS
Authors: Stoimenow A.
Published: May 2003

We treat an enumeration problem of chord diagrams, which is shown to yield an upper bound for the dimension of the space of Vassiliev invariants for knots. We give an asymptotical estimate for this bound. As an aside, we present a trivial proof for the bound D!.
POSITIVE KNOTS AND ROBINSON'S ATTRACTOR
Authors: SULLIVAN MICHAEL C.
Published: May 2003

We study knotted periodic orbits which are realized in an attractor of a certain ODE. These knots can be presented so as to have all positive crossings, but may not be restricted to positive braids.
KNOTS AND LINKS IN INTEGRABLE HAMILTONIAN SYSTEMS
Authors: CASASAYAS J. , ALFARO J. MARTINEZ , NUNES A.
Published: May 2003

The main purpose of this paper is to prove that Bott integrable Hamiltonian flows and non-singular Morse-Smale flows are closely related. As a consequence, we obtain a classification of the knots and links formed by periodic orbits of Bott integrable Hamiltonians on the 3-sphere and on the solid torus. We also show that most of Fomenko's theory on the topology of the energy levels of Bott integrable Hamiltonians can be derived from Morgan's results on 3-manifolds that admit non-singular Morse-Smale flows.
GENERALIZED TEMPERLEY–LIEB ALGEBRAS AND DECORATED TANGLES
Authors: GREEN R. M.
Published: May 2003

We give presentations, by means of diagrammatic generators and relations, of the analogues of the Temperley–Lieb algebras associated as Hecke algebra quotients to Coxeter graphs of type B and D. This generalizes Kauffman's diagram calculus for the Temperley–Lieb algebra.
VASSILIEV INVARIANTS AND ORIENTATION OF PRETZEL KNOTS
Authors: KALFAGIANNI EFSTRATIA
Published: May 2003

We show that Vassiliev invariants of orders ≤ 10 do not detect the change of orientation in a large class of pretzel knots. We also show that for every n ∈ N there exist non-invertible knots that have the same Vassiliev invariants of orders ≤ n, with their inverses.
On the skeins in the annulus and applications to invariants of 3-manifolds
Authors: Kawagoe Kenichi
Published: May 2003

In this paper, we relate Schur functions and a linear skein of annulus derived from the Homfly polynomail. Using this relations, we define topological invariants of 3-manifolds from the Homfly polynomial.
ESSENTIAL TORI IN LINK COMPLEMENTS
Authors: NG KA YI
Published: May 2003

We complete the characterization of essential tori in link complements which was first given in [3], and give a new set of interesting and subtle examples of essential tori.
SPHERE-SLICE LINKS WITH AT MOST FIVE COMPONENTS
Authors: SATOH SHIN
Published: May 2003

A sphere-slice link is a cross-sectional link obtained by cutting a 2-sphere in R4 by a hyperplane. We characterize a sphere-slice link with at most 5 components by linking numbers. We also show that every n-component link is sublink of a (2n+1)-component sphere-slice link and this value is best possible.
STIRLING NUMBERS, EULERIAN IDEMPOTENTS AND A DIAGRAM COMPLEX
Authors: STOIMENOW ALEXANDER
Published: May 2003

We give a homological explanation of the ideals of the Eulerian elements in the ring of the symmetric group in terms of subspaces of relations in the Kohno algebra of singular braid diagrams and discuss some known and new properties of Eulerian elements.
COVERING PROPERTIES OF SMALL VOLUME HYPERBOLIC 3-MANIFOLDS
Authors: MEDNYKH ALEXANDER , VESNIN ANDREI
Published: May 2003

Closed hyperbolic 3-manifolds obtained by Dehn surgeries on the Whitehead link yield interesting examples of manifolds of small volume. In the present paper these manifolds are described as 2-fold coverings of the 3-sphere branched over 3-bridge links. As a corollary, maximally symmetric [Formula: see text]-manifolds of small volume are obtained.
A LIMITATION ON ALGORITHMS FOR CONSTRUCTING MINIMAL ARC-PRESENTATIONS FROM LINK DIAGRAMS
Authors: BELTRAMI ELISABETTA , CROMWELL PETER R.
Published: May 2003

The arc index of a link is closely related to its crossing number. An algorithm is known which produces an arc-presentation by drawing the binding circle on a link diagram. When the algorithm can be applied and the link is alternating, the presentation is known to be minimal. Here we exhibit an example which shows that no such algorithm can be valid for all link diagrams.
ESSENTIAL LAMINATIONS, EXCEPTIONAL SEIFERT-FIBERED SPACES, AND DEHN FILLING
Authors: BRITTENHAM MARK
Published: May 2003

We show how essential laminations can be used to provide an improvement on (some of) the results of the 2π-Theorem; at most 20 Dehn fillings on a hyperbolic 3-manifold with boundary a torus T can yield a reducible manifold, finite π1 manifold, or exceptional Seifert-fibered space. Recent work of Wu allows us to add toroidal manifolds to this list, as well.
VASSILIEV LINK INVARIANTS OF ORDER THREE
Authors: KANENOBU TAIZO , MIYAZAWA YASUYUKI , TANI AKIKO
Published: May 2003

We express a basis for the space of all Vassiliev invariants of order less than or equal to three for an ordered oriented link in terms of the Conway polynomials, the linking numbers, and the HOMFLY polynomials. An applications, we give a formula relating to the Casson-Walker invariant of 3-manifolds from a result of Kirk and Livingston, and give a new proof for a formula of Hoste concerning the coefficient of the Conway polynomial of a link.
IDEMPOTENTS OF HECKE ALGEBRAS OF TYPE A
Authors: AISTON A. K. , MORTON H. R.
Published: May 2003

We use a skien-theoretic version of the Hecke algebras of type A to present three-dimensional diagrammatic views of Gyoja's idempotent elements, based closely on the corresponding Young diagram λ. In this context we give straightforward calculations for the eigenvalues fλ and mλ of two natural central elements in the Hecke algebras, namely the full curl and the sum of the Murphy operators. We discuss their calculation also in terms of the framing factor associated to the appropriate irreducible representation of the quantum group, SU(N)q.
PARALLELISM OF TWO STRINGS IN ALTERNATING TANGLES
Authors: SHIMOKAWA KOYA
Published: May 2003

We consider the parallelism of two strings in alternating tangles. We show that if there is a pair of parallel strings in an alternating tangle then its alternating diagrams satify certain conditions. As a corollary, for a knot admitting a decomposition into two alternating tangles with two or three strings, we prove that its non-trivial Dehn surgery yields a 3-manifold with an essential lamination. Hence such a knot has property P and satisfy the cabling conjecture.
HIGH DIMENSIONAL KNOT GROUPS AND HNN EXTENSIONS OF THE FIBONACCI GROUPS
Authors: SZCZEPAŃSKI ANDRZEJ
Published: May 2003

We shall present a new class of examples of high dimensional knot groups. All of them are HNN extensions of the Fibonacci groups. We give also some characterization of these groups.
REGULAR PROJECTIONS OF KNOTTED HANDCUFF GRAPHS
Authors: TANIYAMA KOUKI , YOSHIOKA CHIZU
Published: May 2003

We construct an infinite set of knotted handcuff graphs such that the set of the regular projections of the handcuff graphs in the set equals the set of the regular projections of all knotted handcuff graphs. We also show that no finite set of knotted handcuff graphs have this property.
THE BASIC INVARIANTS OF LONG CURVE AND CLOSED CURVE PERESTROIKAS
Authors: ZHOU Jianyi , ZOU Jiancheng , PAN Jianzhong
Published: May 2003

We give the relations between invariants of closed curves and that of long curves. By these relations we study all extremal values of invariants of long curves via which of closed curves and give the explicite formulas for these extremal values.
THERE ARE NO STRICT GREAT x-CYCLES AFTER A REDUCING OR P2 SURGERY ON A KNOT
Authors: HOFFMAN JAMES A.
Published: May 2003

The Cabling conjecture states that Dehn surgery on a nontrivial knot K in S3 yields a reducible manifold only when K is a nontrivial cabled knot. One idea is to attack this problem with the techniques used by Gordon and Luecke in the Knot Complement Problem. This involves a combinatorial analysis of two intersecting planar graphs. In the context of reducible surgery, one of the two planar graphs will necessarily contain a Scharlemann cycle. So, we define a strict x-cycle to be any x-cycle which is not a Scharlemann cycle; likewise, for strict great x-cycles. We show that if the reducing sphere meets the core of the Dehn filling minimally, then strict great x-cycles are not permitted. Thus, strict great x-cycles can play a role similar to that of the Scharlemann cycle in the Knot Complement Problem. The obstruction of finding strict great x-cycles is considered an essential step in the program.

A second conjecture states that Dehn surgery on a nontrivial knot K in S3 yields a manifold containing an embedded projective plane only when K is a nontrivial cabled knot. We show how the Gordon and Luecke technique can be applied towards this conjecture by considering the spherical boundary of a regular neighborhood of the projective plane. And if the projective plane is chosen to meet the core of the Dehn filling minimally, we show that strict great x-cycles are not permitted.
ADDITIVITY PROPERTIES OF MILNOR'S ${\bar\mu}$-INVARIANTS
Authors: KRUSHKAL VYACHESLAV S.
Published: May 2003

We prove that Milnor's [Formula: see text]-invariants are additive under the connected sum operation for links, and establish some corollaries of this result. The appendix describes a technique for finding presentations of nilpotent quotients of groups, and a lemma helpful for locating gropes in the complement of surfaces in four-space.
DELTA-UNKNOTTING NUMBER FOR KNOTS
Authors: NAKAMURA K. , NAKANISHI Y. , UCHIDA Y.
Published: May 2003

The Δ-unknotting number for a knot is defined to be the minimum number of Δ-unknotting operations which deform the knot into the trivial knot. We determine the Δ-unknotting numbers for torus knots, positive pretzel knots, and positive closed 3-braids.
A LEGENDRIAN STRATIFICATION OF RATIONAL TANGLES
Authors: TRAYNOR LISA
Published: May 2003

A subset of legendrian 2-string tangles are defined to be minimal if the strands realize the minimum absolute value of the Bennequin invariant. The restrictiveness of this condition is examined by studying which topological rational tangles have minimal representatives. It is shown that a rational of finite parity has a minimal representative if and only if its standard continued fraction expansion contains only non-negative entries, is of odd length, and has every horizontal entry even. This is proved by applying recent results of Fuchs and Tabachnikov or Chmutov and Goryunov that give an upperbound for the Bennequin invariant of links in terms of the minimal exponent of the framing variable of the Kauffman polynomial and Yokota's precise formula for this topological invariant. A second geometric stratum of rational tangles with infinite parity is defined and it is then shown a positive rational has a minimal represenative if and only if its continued fraction expansion is a particular extension of a minimal of finite parity and a negative rational of infinite parity has a minimal representative if and only if it has even length with every vertical entry even.
ON VASSILIEV INVARIANTS FOR LINKS IN HANDLEBODIES
Authors: VERSHININ VLADIMIR V.
Published: May 2003

The notion of Vassiliev algebra in case of handlebodies is developed. Analogues of the results of J. Baez for links in handlebodies are proved. This implies that there is a one-to-one correspondence between the special class of finite type invariants of links in hanlebodies and the homogeneous Markov traces on Vassiliev algebras. This approach uses the singular braid monoid and braid group in a handlebody and the generalizations of the theorem of J. Alexander and the theorem of A. A. Markov for singular links and braids and the relative version of Markov's theorem.
A NOTE ON THE #-UNKNOTTING OPERATION
Authors: ASKITAS N.
Published: May 2003

We use a connection between local moves on knots and the singularity type of certain PL-spheres in 4-manifolds and use it to recover (stronger in principle versions of) known results as well as obtain new ones regarding certain #-unknotting numbers of knots.
Combinatorial suspension for disc homeomorphisms
Authors: Gautero François , Los Jérôme
Published: May 2003

For a punctured disc homeomorphism given combinatorially, we give an algorithmic construction of the suspension flow in the corresponding mapping-torus M3. In particular, one computes explicitly the embedding in the 3-manifold M3 of any finite collection of periodic orbits for this flow. All these orbits are realized as closed braids carried by a branched surface (or template), which we construct in the algorithm. Our construction gives a combinatorial proof of the fact that the periodic orbits of such a suspension flow are carried by a same branched surface.
AN UPPER BOUND ON EDGE NUMBERS OF 2-BRIDGE KNOTS AND LINKS
Authors: MCCABE CYNTHIA L.
Published: May 2003

A method is given for economically constructing any 2-bridge knot or link K. This construction gives an upper bound of c(K) + 3 for the edge number of K, except in the case of the unlink and the Hopf link, and has the added advantage of realizing a projection with c(K) crossings.
ON VASSILIEV INVARIANTS FOR ALGEBRAICALLY SPLIT LINKS
Authors: OKAMOTO MIYUKI
Published: May 2003

We confine our attention to an algebraically split link and prove that any Vassiliev invariant of type d can be described in terms of the invariants of sublinks with d - 1 or less components of the link. Further the contributions from (d - 1)-component sublinks in the formula turn out to be the d-th coefficients of the Conway polynomials of the sublinks.
MULTI-# UNKNOTTING OPERATIONS: A NEW FAMILY OF LOCAL MOVES ON A KNOT DIAGRAM AND RELATED INVARIANTS OF KNOTS
Authors: ASKITAS N.
Published: May 2003

We define new families of (so called multi-#) local moves on knot projections (which contain the #-local move and the ordinary crossing change) and study some of their properties together with related knot invariants. We show that they define unknotting operations and hence resulting unknotting numbers. We use 4-manifold theory as a tool and more specifically P. Gilmer's thesis ([3]).
THE SINGULAR BRAID MONOID EMBEDS IN A GROUP
Authors: FENN ROGER , KEYMAN EBRU , ROURKE COLIN
Published: May 2003

We prove that the singular braid monoid of [2] and [5] embeds in a group. This group has a geometric interpretation as singular braids with two type of singularities which cancel.
SL(2, C)-TOPOLOGICAL QUANTUM FIELD THEORY WITH CORNERS
Authors: GELCA RĂZVAN
Published: May 2003

In this paper we define the sl(2, C) topological quantum field theory with corners that corresponds to the smooth theory of Reshetikhin and Turaev. We encounter a sign obstruction at the level of the modular functor, which we solve by making use of the Klein four group. We deduce the Moore-Seiberg equations in the new context.
SIMPLE 4-KNOTS
Authors: HILLMAN J. A. , KEARTON C.
Published: May 2003

We show that the isotopy type of a 1-simple n-knot K is determined by the Postnikov (n - 1)-stage of its exterior X(K), together with the homotopy class of the longitude λK ∈ πn(X(K)). Moreover any pair (X, j) where X is a 4-dimensional homology circle with π1(X) ≅ Z and j : S4 × S1 → X is such that (X, j) = (MCyl(j), S4 × S1) is an orientable PD6-pair is realizable by some simple 4-knot. We derive complete algebraic characterizations of torsion free fibred simple 4-knots and of Artin spins of fibred simple 3-knots.
DISTINGUISHING LINK-HOMOTOPY CLASSES BY PRE-PERIPHERAL STRUCTURES
Authors: HUGHES JAMES R.
Published: May 2003

An open problem in link-homotopy of links in S3 is classification using peripheral invariants, analogous to that of Waldhausen for links up to ambient isotopy. An approach to such a classification was outlined by Levine, but shown not to be feasible by the author. Here, we develop an approach to finding classification counterexamples. The approach requires non-injectivity of a group homomorphism that is completely determined by minimal-weight commutator numbers (equivalent to the first non-vanishing [Formula: see text] invariants of Milnor). For non-injectivity, the minimal-weight commutator numbers must all be non-zero, and satisfy a certain system of polynomials, which we compute for 4- and 5-component links.
FREE GENUS ONE KNOTS DO NOT ADMIT ESSENTIAL TANGLE DECOMPOSITIONS
Authors: MATSUDA HIROSHI , OZAWA MAKOTO
Published: May 2003

In this paper, we show that free genus one knots do not admit essential tangle decompositions.
GENERALIZATION OF ARNOLD'S INVARIANTS OF PLANE CURVES
Authors: SCHEIBLING ELVIRE
Published: May 2003

Considering functions of index at jumps on non-generic curves instead of constants, we define invariants generalizing Arnold's invariants of plane curves. We construct three families of such invariants. We prove that each of these new invariants can be written as a sum of three representatives of these families.
ON THE STRUCTURE AND SCARCITY OF ALTERNATING LINKS AND TANGLES
Authors: THISTLETHWAITE MORWEN
Published: May 2003

It is shown that the proportion of alternating n-crossing, prime link types amongst all n-crossing prime link types tends to zero exponentially with increasing n. Also, a characterization is established for essential annuli in alternating tangles, and a simple criterion is given for equivalence of alternating tangles.
SURFACES IN THE FIGURE-8 KNOT COMPLEMENT
Authors: AITCHISON I. R. , MATSUMOTO S. , RUBINSTEIN J. H.
Published: May 2003

We examine various closed normal surfaces immersed in the triangulated figure-8 knot complement. We give some conditions for surfaces to be regular (without branch points) and a sufficient condition for compressibility. We end with a criterion for incompressibility of normal surfaces in cubed 3-manifolds.
REGULAR HOMOTOPY AND VASSILIEV INVARIANTS OF GENERIC IMMERSIONS Sk → ℝ2k-1, k ≥ 4
Authors: EKHOLM TOBIAS
Published: May 2003

The regular homotopy class of a generic immersion Sk → ℝ2k-1 is calculated in terms of its self intersection manifold with natural additional structures.

There is a natural notion of Vassiliev invariants of generic immersions. These may take values in any Abelian group G. It is proved that, for any m, the group of mth order G-valued invariants modulo invariants of lower order is isomorphic to G and that the Vassiliev invariants are not sufficient to separate generic immersions, which can not be obtained from each other by a regular homotopy through generic immersions.
A REAPPEARANCE OF WHEELS
Authors: GAROUFALIDIS STAVROS
Published: May 2003

Recently, a number of authors [KS, Oh2, Ro] have independently shown that the universal finite type invariant of rational homology 3-spheres on the level of [Formula: see text] can be recovered from the Reshetikhin-Turaev [Formula: see text] invariant. An important role in Ohtsuki's proof [Oh3] plays a map j1 (which joins the legs of 2-legged chinese characters) and its relation to a map α in terms of a power series (on the level of [Formula: see text]). The purpose of the present note is to give a universal formula of the map α in terms of a power series F of wheel chinese characters. The above formula is similar to universal formulas of wheel chinese characters considered in [BGRT1] and leads to a simple conceptual proof of the above mentioned relation between the maps j1 and α on the level of [Formula: see text].
HEEGAARD SPLITTINGS OF THE TRIVIAL KNOT
Authors: HAYASHI CHUICHIRO , SHIMOKAWA KOYA
Published: May 2003

We show that any Heegaard splitting of the trivial knot in a compact orientable 3-manifold is standard.
ON FRAMED LINK PRESENTATIONS OF SURFACE BUNDLES
Authors: ICHIHARA KAZUHIRO
Published: May 2003

In this paper, we show that every closed orientable surface bundle over the circle is represented by a fibered link in the 3-sphere with framings induced by the fibration of the complement.
RECURSIVE CALCULATION FOR AN INVARIANT OF A RIBBON KNOT
Authors: KANENOBU TAIZO
Published: May 2003

We give an algorithm for calculating the second degree coefficient of the Conway polynomial of a ribbon 1-knot. This naturally yields a recursive calculation for the second derivative at t = 1, Δ′′(1), of the normalized Alexander polynomial of a ribbon 2-knot in R4, which is the first nontrivial finite type invariant of a ribbon 2-knot defined by Habiro, Kanenobu, and Shima.
HOPF-BRAID GROUPS
Authors: MOULTON VINCENT
Published: May 2003

In this note we define the Hopf-braid group, a group that is directly related to the group of motions of n mutually distinct lines through the origin in [Formula: see text], which is better known as the braid group of the two-sphere. It is also related to the motion group of the Hopf link in the three-sphere. This relationship is provided by considering the link of a union of complex lines through the origin in [Formula: see text] (i.e. the intersection of the lines with the unit 3-sphere centered at the origin in [Formula: see text]). Through the study of this group we also illustrate some of the connections between the field of knots and braids and that of hyperplane arrangements.
COOPERATIVE INFORMATION SYSTEMS: INTEROPERABILITY IN HEALTH CARE LEGACY APPLICATIONS
Authors: MURPHY JOHN , GRIMSON JANE
Published: May 2003

We believe that the typical hospital computing environment is especially fruitful as a domain for investigating the problems of interoperability and cooperation. We state this belief as hospital computing environments consist of a heterogeneous collection of autonomous information systems. These systems range from centralised hospital-wide systems, such as patient administration systems, to departmental systems such as pharmacy stock-control, laboratory information systems, accident and emergency systems and so on. Many of these are legacy systems which have been operating for many years and are difficult to integrate and virtually impossible to rewrite. In this article we discuss and assess the work of the Jupiter Project and its successor LIOM (Legacy system Interoperability using Object-oriented Methods).
ENFORCEMENT OF INTER-TASK DEPENDENCIES IN WORKFLOWS, CHARACTERIZATION AND PARADIGM
Authors: TANG JIAN , VEIJALAINEN JARI
Published: May 2003

Workflow techniques have gained a lot of attention as a means to support advanced business applications such as cooperative information systems and process re-engineering but also as a means to integrate legacy systems. Inter-task dependencies, described separately from the other parts of the workflow, have been recognized as a valuable method in describing certain restrictions on the executions of workflows. In this paper, we study the issue of pre-analysing and enforcing inter-task dependencies. The protocol and the theory behind it are presented, along with examples and discussions on ways to improve the performance. The idea is to present the meaning of a dependency through an automaton which accepts the sequences of events tied by the dependency through an automaton which accepts the sequences of events tied by the dependency. We prune from the automata certain paths that cannot be followed due to the conflicting paths in other automata and record the feasible event sequences in a special data structure to be used during run-time. We show the correctness of the algorithms and also show that our run-time algorithm is linear, whereas the original approach suggested by MCC in Refs. 5 and 6 is exponential, when resolution of one event is concerned.
LOOSELY-SPECIFIED QUERY PROCESSING IN LARGE-SCALE INFORMATION SYSTEMS
Authors: NICA ANISOARA , RUNDENSTEINER ELKE A.
Published: May 2003

Challenging issues for processing queries specified over large-scale information spaces (e.g., Digital Libraries or the World Wide Web) include the diversity of the information sources in terms of their structures, query interfaces and search capabilities, as well as the dynamics of sources continuously being added, removed or upgraded. In this paper, we give an innovative solution for query planning in such environments. The foundation of our solution is the Dynamic Information Integration Model (DIIM) which supports the specification of not only content but also capabilities of resources without requiring the establishment of a uniform integration schema. Besides the development of the DIIM model, contributions of this paper include: (1) the introduction of the notion of fully specified queries that are semantically equivalent to a loosely-specified query; (2) a translation algorithm of a loosely-specified query into a set of semantically equivalent feasible query plans that are consistent with the binding patterns of query templates of the individual sources (capability descriptions in DIIM) and with interrelationships between informations sources (expressed as join constraints in DIIM); and (3) a search restriction algorithm for optimizing query processing by pruning the search space into the relevant subspace of a query. The plans obtained by the proposed query planning process which is composed of the search restriction and translation algorithms can be shown to correspond to query plans semantically equivalent to the initial loosely-specified input query.
FINDING MULTIPLE LOCAL MINIMA USING CHAOTIC JUMP
Authors: CHOI CHANGKYU , LEE JU-JANG
Published: May 2003

In this paper, the local minima free search algorithm using chaos is proposed for an unstructured search space. The problem is that given the quality function, find the value of a configuration that minimizes the quality function. The proposed algorithm started basically from the gradient search technique but at the prescribed points, that is, local minimum points, which are to be automatically detected the chaotic jump is introduced by the dynamics of a chaotic neuron. Chaotic motions are mainly because of the Gaussian function having a hysteresis as a refractoriness. In order to enhance the probability of finding the global minimum, a parallel search strategy is also given. The validity of the proposed method wil be verified in simulation examples of the function minimization problem and the motion planning problem of a mobile robot.
A SPATIAL/TEMPORAL QUERY LANGUAGE FOR MULTIPLE DATA SOURCES IN A HETEROGENEOUS INFORMATION SYSTEM ENVIRONMENT
Authors: CHANG SHI-KUO , JUNGERT ERLAND
Published: May 2003

To support the retrieval, fusion and discovery of multimedia information, a spatial/temporal query language for multiple data sources is needed. In this paper we describe a spatial/temporal query language, the ∑QL, which is based upon the σ-operator sequence and in practice expressible in an SQL-like syntax. The general σ-operator and temporal σ-operator are explained, and applications of the σ-query language to vertical/horizontal reasoning and hypermapped virtual world are discussed.
WAG: WEB-AT-A-GLANCE
Authors: CATARCI TIZIANA , NARDI DANIELE , SANTUCCI GIUSEPPE , CHANG S. K.
Published: May 2003

The Internet revolution has made an enormous quantity of information available to a disparate variety of people. The amount of information, the typical access modality (that is, browsing), and the rapid growth of the Net, force the user, while searching for the information of interest, to dip into multiple sources, in a labyrinth of millions of links. Web-at-A-Glance (WAG) is a system allowing the user to query (instead of browsing) the Web. WAG performs this ambitious task by constructing a personalized database, pertinent to the user's interests. The system semi-automatically gleans the most relevant information from a Web site or several Web sites, stores them into a database cooperatively designed with the user, and allows her/him to query such a database through a visual interface equipped with a powerful multimedia query language. This paper presents the design philosophy, the architecture and the core of the WAG system. A prototype WAG is being implemented to test the feasibility of the proposed approach.
THE DIMENSIONAL FACT MODEL: A CONCEPTUAL MODEL FOR DATA WAREHOUSES
Authors: GOLFARELLI MATTEO , MAIO DARIO , RIZZI STEFANO
Published: May 2003

Data warehousing systems enable enterprise managers to acquire and integrate information from heterogeneous sources and to query very large databases efficiently. Building a data warehouse requires adopting design and implementation techniques completely different from those underlying operational information systems. Though most scientific literature on the design of data warehouses concerns their logical and physical models, an accurate conceptual design is the necessary foundations for building a DW which is well-documented and fully satisfies requirements. In this paper we formalize a graphical conceptual model for data warehouses, called Dimensional Fact model, and propose a semi-automated methodology to build it from the pre-existing (conceptual or logical) schemes describing the enterprise relational database. The representation of reality built using our conceptual model consists of a set of fact schemes whose basic elements are facts, measures, attributes, dimensions and hierarchies; other features which may be represented on fact schemes are the additivity of fact attributes along dimensions, the optionality of dimension attributes and the existence of non-dimension attributes. Compatible fact schemes may be overlapped in order to relate and compare data for drill-across queries. Fact schemes should be integrated with information of the conjectured workload, to be used as the input of logical and physical design phases; to this end, we propose a simple language to denote data warehouse queries in terms of sets of fact instances.
SUPPORTING ELECTRONIC COMMERCE TRANSACTIONS WITH CONTRACTING SERVICES
Authors: MERZ MICHAEL , GRIFFEL FRANK , TU TUAN , MÜLLER-WILKEN STEFAN , WEINREICH HARALD , BOGER MARKO , LAMERSDORF WINFRIED
Published: May 2003

Based on the specific characteristics and requirements for an adequate electronic commerce system support, this article gives an overview of the respective distributed systems technologies which are available for open and heterogeneous electronic commerce applications. Abstracting from basic communication mechanisms such as (transactionally secure) remote procedure calls and remote database access mechanisms, this includes service trading and brokerage functions as well as security aspects including such as notary and non-repudiation functions. Further important elements of a system infrastructure for electronic commerce applications are: Common middleware infrastructures, componentware techniques, distributed and mobile agent technologies etc. As electronic transactions enter the phase of performance, increasingly new and important functions are required. Among these are: Negotiation protocols to support both the settlement and fulfillment of electronic contracts as well as ad-hoc workflow management support for compound and distributed services in electronic commerce applications. In addition to an overview of the state of the art of the respective technology, the article briefly presents some related projects conducted by the authors jointly with international partners in order to realize some of the important new functions of a system infrastructure for open distributed electronic commerce applications.
COMBINING STRUCTURED DOCUMENTS WITH HIGH-LEVEL PETRI-NETS FOR WORKFLOW MODELING IN INTERNET-BASED COMMERCE
Authors: WEITZ WOLFGANG
Published: May 2003

This article discusses the application of a new variant of high-level Petri nets, the so-called SGML nets, for modeling business processes in the area of Internet-based commerce. SGML nets are designed to capture the process of generating and manipulating structured documents based on the international standard SGML. Since the currently most relevant document standards on the Internet are HTML (an SGML application) and XML (a subset of SGML), SGML nets offer an elegant way to integrate central aspects of Electronic Commerce applications, such as the generation of online product catalogs, processing of online orders, and electronic document interchange between companies, into a unified formal workflow model. The article gives an introduction to the central concepts of SGML nets and includes an example of their application from the area of online order processing.
MARKET-BASED WORKFLOW MANAGEMENT
Authors: GEPPERT ANDREAS , KRADOLFER MARKUS , TOMBROS DIMITRIOS
Published: May 2003

This paper presents market-based workflow management, a novel approach to work-flow specification and execution which regards tasks performed in a workflow as goods traded in an electronic market. Information about expected cost and execution time is considered for activity specifications, and is used at runtime to execute workflows such that actual cost and execution times are balanced and optimized. To that end, task assignment follows a bidding protocol, in which each eligible processing entity specifies at which price and in which time interval it can execute the activity. The winner of a specific bidding process is requested to execute the activity, and earns the amount specified in the corresponding bid. Market-based workflow management thus allows to optimize workflow executions with respect to execution time and overall cost; additionally the trading of activities provides an incentive for processing entities to engage in a workflow.
AN ELECTRONIC BROKER FOR BUSINESS-TO-BUSINESS ELECTRONIC COMMERCE ON THE INTERNET
Authors: BICHLER MARTIN , SEGEV ARIE , BEAM CARRIE
Published: May 2003

Distributed object standards provide a key to building interoperable applications that can run on a range of platforms. The paper describes a CORBA-based research prototype for an electronic broker in business-to-business electronic commerce. High-level IDL specifications are used to achieve interoperability between components of the electronic marketplace. The two key functionalities of the electronic broker are the ability to dynamically gather information from remote electronic catalogs and the support for negotiations through auction mechanisms. The paper discusses the functionality and the design of the electronic broker and gives an overview of current extensions of the prototype. As application-level interoperability is a crucial precondition for many brokerage services, we put special emphasis on electronic commerce protocol standards.
A SAFE AND SCALABLE PAYMENT INFRASTRUCTURE FOR TRADE OF ELECTRONIC CONTENT
Authors: SHAMIR GADI , BEN-OR MICHAEL , DOLEV DANNY
Published: May 2003

BARTER (a Backbone ARchitecture for Trade of ElectRonic content) is a payment infrastructure that facilitates digital content trade over an open network. BARTER is designed to operate over a large-scale, global and heterogeneous communication network. The BARTER protocols address two vital requirements, neglected from existing electronic commerce systems: scalability and transactional efficiency. These protocols possess strong properties such as delivery atomicity, agreement validation and the ability to resolve several classes of disputes. BARTER's novelty is twofold: First, BARTER servers are not required to perform expensive cryptographic operations such as commitment verification; commitments are cross-verified by the parties themselves, thus reducing the overhead of online transaction processing by orders of magnitude. Consequently, BARTER can serve as an efficient online/offline clearing infrastructure. Second, BARTER integrates scalability considerations into several system components (the authentication subsystem, the account management subsystem, and the maintenance of global data) that are likely to suffer service degradation in a world-wide setting. In addressing these issues, BARTER takes into account the inherent asynchronous, unreliable, insecure and failure-prone environment assumptions. We contend that by employing service distribution, BARTER is expected to scale well, meeting the demands of a world-wide setting, over which it is intended to operate.
RELIABILITY CONCEPTS FOR MOBILE AGENTS
Authors: STRASSER MARKUS , ROTHERMEL KURT
Published: May 2003

The use of mobile agent technology has been proposed for various fault-sensitive application areas, including electronic commerce and system management. A prerequisite for the use of mobile agents in these environments is that agents have to be executed reliably, independent of communication and node failures.

In this article, we present two approaches improving the level of fault-tolerance in agent execution. The introduction of an itinerary concept allows to specify an agent's travel plan flexibly and provides the agent system with the possibility to postpone the visit of currently unavailable nodes or to choose alternative nodes in case of node failures.

The second approach is a recently proposed fault-tolerant protocol to ensure the exactly-once execution of an agent. With this protocol, agents are preformed in stages. Each stage consists of a number of nodes. One of these nodes executes the agent while the others monitor the execution. After a summary of this protocol, we focus on the construction of stages. In particular, we investigate how the number of nodes per stage influences the probability of an agent to be blocked due to failures and which nodes should be selected when forming a stage to minimize the protocol overhead.
Mixing beliefs among interacting agents
Authors: Deffuant Guillaume , Neau David , Amblard Frederic , Weisbuch Gérard
Published: June 2003

We present a model of opinion dynamics in which agents adjust continuous opinions as a result of random binary encounters whenever their difference in opinion is below a given threshold. High thresholds yield convergence of opinions towards an average opinion, whereas low thresholds result in several opinion clusters: members of the same cluster share the same opinion but are no longer influenced by members of other clusters.
Modeling of Social Processes Based on T.Parsons Ideas
Authors: Laptev Alexander A.
Published: June 2003

The goal of our work is to attempt and describe social processes in a mathematical language and to build a system of differential equations describing global evolution of the society. We build a model of social process with a periodic (cyclic) stable solution.
A spatial microsimulation of population dynamics in Southern France: a model integrating individual decisions and spatial constraints
Authors: Aschan-Leygonie C. , Mathian H. , Sanders L. , Mäkilä K.
Published: June 2003

The aim is to model the spatial distribution of the population dynamics in Southern France. First the philosophical differences between a micro-level approach and a meso-level approach are presented and their respective advantages are briefly compared from a general point of view. Then the model is presented. It is a microsimulation model but it has some rules defined at the aggregate level of the communes. Change occur through events as birth, death and migration. that depend on probabilities that are linked to different individuals characteristics as sex, age etc. Four scenarios of development are tested and some future improvements are proposed.
Modelling urban phenomena with cellular automata
Authors: Vanbergue Diane , Treuil Jean-Pierre , Drogoul Alexis
Published: June 2003

Multi-agents systems are frequently used to study complex phenomena and offer tools that interest urban specialists. The aim of this article is to present an example of an approach on the phenomenon of intra-urban migration in Bogota. Our model is based on one of the simplest form of multi-agent systems, kind of cellular automata, where migrants are seen as population flow. It allows us to build an artificial city, based on real census, and also to represent the behaviour of the population, determined by its representation of the different districts. This paper presents the formalism of the model and some results.
Modelling spatial practices and social representations of space using multi-agent systems
Authors: Bonnefoy Jean-Luc , Le Page Christophe , Rouchier Juliette , Bousquet François
Published: June 2003

This paper demonstrates that multi-agent systems have the capacity to model a region in all its complexity. An example is developed to show that these tools are not only capable of spatializing and distributing the behaviour of individuals, but above all, that they allow individuals to integrate different perceptions of space as well as the constraints imposed on them by a community. A dialectic is established between individuals, spaces and society, which is used to simulate a region using clearly defined social representations and spatial practices, which are suitable for testing our geographical theories and hypotheses.
Computer simulations of voting systems
Authors: Lepelley Dominique , Louichi Ahmed , Valognes Fabrice
Published: June 2003

All voting procedures are susceptible to give rise, if not to paradoxes, at least to violations of some democratic principles. In this paper, we evaluate and compare the propensity of various voting rules -belonging to the class of scoring rules- to satisfy two versions of the majority principle. We consider the asymptotic case where the numbers of voters tends to infinity and, for each rule, we study with the help of Monte Carlo methods how this propensity varies as a function of the number of candidates.
Dreamscape Testing the Rational Choice Theory
Authors: Lepperhoff Niels
Published: June 2003

This work is an example for the use of computer simulation for testing theory completeness. The multi-agent model Dreamscape is a transformation of the Rational Choice Theory into a computer program. In this work the general applicability of the Rational Choice Theory is tested. The research question is: Does social order emerge out of the "state of nature"? In particular: Do social norms evolve? In a computer-based analysis for non-violent agents it is shown, that conjunct, proscriptive norms are able to emerge – apart from their legitimacy. On the contrary, in a violent population social order does not emerge.
Multi-Agent Modelling of Resource Systems and Markets: Theoretical consideration and simulation results
Authors: Beckenbach Frank
Published: June 2003

In section 2 the importance of mas for the modern debate in non-canonized economic theory is sketched. Taking resource constraints, bounded rationality and local interaction as basic features of such a debate a mas architecture in which these features are present is provided in section 3. In section 4 conclusions are drawn and lines of further research are outlined.
Cooperation in an Adaptive Network
Authors: Zimmermann M. G. , Eguíluz V. M. , San Miguel M. , Spadaro A.
Published: June 2003

We study the dynamics of a set of agents distributed in the nodes of an adaptive network. Each agent plays with all its neighbors a weak prisoner's dilemma collecting a total payoff. We study the case where the network adapts locally depending on the total payoff of the agents. In the parameter regime considered, a steady state is always reached (strategies and network configuration remain stationary), where co-operation is highly enhanced. However, when the adaptability of the network and the incentive for defection are high enough, we show that a slight perturbation of the steady state induces large oscillations (with cascades) in behavior between the nearly all-defectors state and the all-cooperators outcome.
Generalized Lotka-Volterra (GLV) Models of Stock Markets
Authors: Solomon Sorin
Published: June 2003

The Generalized Lotka-Volterra (GLV) model: [Formula: see text] provides a general method to simulate, analyze and understand a wide class of phenomena that are characterized by power-law probability distributions: [Formula: see text] and truncated Levy flights fluctuations [Formula: see text]. We show how the model applies to economic systems.