A Note on Old Babylonian Computational Techniques

Analysis of the errors in two Old Babylonian “algebraic” problems shows

• •that the computations were performed on a device where additive contributions were no longer identifiable once they had entered the computation;
• •that this device must have been some kind of counting board or abacus where numbers were represented as collections of calculi;
• •that units and tens were represented in distinct ways, perhaps by means of different calculi.

© 2002 Elsevier Science (USA).Eine Analyse der Rechenfehler in zwei altbabylonischen “algebraischen” Aufgaben läßt mehrere Rückschlüsse auf ein Hilfsmittel zu, das zur Durchführung von Rechnungen benutzt worden sein kann:

• •Additive Beiträge waren nach ihrer Eintragung in die Rechnung nicht länger identifizierbar.
• •Das Gerät war eine Art Rechenbrett, auf welchem Zahlen als Haufen von Rechensteinen erschienen.
• •Einer und Zehner wurden in verschiedener Weise, evtl. mittels verschiedener Rechensteine repräsentiert.

© 2002 Elsevier Science (USA).MSC subject classification: 01A17.     

Computing over the Reals with Addition and Order: Higher Complexity Classes

This paper deals with issues of structural complexity in a linear version of the Blum-Shub-Smale model of computation over the real numbers. Real versions of PSPACE and of the polynomial time hierarchy are defined, and their properties are investigated. Mainly two types of results are presented:

• •Equivalence between quantification over the real numbers and over {0, 1};
• •Characterizations of recognizable subsets of {0, 1}* in terms of familiar discrete complexity classes.

The complexity of the decision and quantifier elimination problems in the theory of the reals with addition and order is also studied.     

Symplectic geometry,minors and graph Laplacians

In my talk, I will present some works done in the nineties on Laplacians on graphs: from eigenvalue problems to inverse problem for resistor networks. I will focus on the motivations and the main results as well as on the main ideas:

• •A differential topology point of view on the minor relation: a nice stratification associated to a finite graph Γ whose strata are associated to the minors of Γ
• •“Discrete” (graphs) versus “continuous” (Riemannian manifolds)
• •Stability of spectra with respect to singular limits: a finite dimensional theory of operators with domains (Von Neumann theory).

The link with topology will appear in some results about my graph parameter μ, in particular the planarity and the linkless embedding properties.     

Analysis of performance of an iron-bath reactor using computational fluid dynamics

The performance of an iron-bath reactor has been studied using a comprehensive numerical model that combines a computational fluid dynamics approach for the gas phase and a heat and mass balance model for the bath. The model calculates:

• •coal, ore, flux and oxygen consumption;
• •post-combustion ratio (PCR);
• •heat-transfer efficiency (HTE);
• •off-gas temperature and composition;
• •heat transfer and chemical reactions between gas and iron and slag droplets; and
• •heat transfer between gas and bath, refractories and lance.

The model was validated with data reported by the Nippon Steel Corporation for a 100 t pilot plant, and the calculated and measured data are in good agreement. Modelling results showed that the dominant mechanisms of heat transfer from the gas to the bath are radiation to the slag surface and convection heat transfer to droplets.     

Softness of hypercoherences and MALL full completeness

We prove a full completeness theorem for multiplicative–additive linear logic (i.e. MALL) using a double gluing construction applied to Ehrhard’s *-autonomous category of hypercoherences. This is the first non-game-theoretic full completeness theorem for this fragment. Our main result is that every dinatural transformation between definable functors arises from the denotation of a cut-free MALL proof.Our proof consists of three steps. We show:

• •Dinatural transformations on this category satisfy Joyal’s softness property for products and coproducts.
• •Softness, together with multiplicative full completeness, guarantees that every dinatural transformation corresponds to a Girard MALL proof-structure.
• •The proof-structure associated with any dinatural transformation is a MALL proof-net, hence a denotation of a proof. This last step involves a detailed study of cycles in additive proof-structures.

The second step is a completely general result, while the third step relies on the concrete structure of a double gluing construction over hypercoherences.     

Maximizing profit of a food retailing chain by targeting and promoting valuable customers using Loyalty Card and Scanner Data

In this paper, we set up a House of Profit Model, an approach of maximizing profit of a food retailing chain by targeting and promoting valuable customers. Our model combines

• •segmentation analysis of households using Loyalty Card and Scanner Data,
• •price and promotion elasticity analysis,
• •simulation of effects of pricing and promotion,
• •price and promotion optimization to maximize profit.

These components are well-known in the literature and each of them has received considerable independent study. However, in this study we combine each of these components into one consistent, application-orientated model. We then demonstrate using panel data that the combination has a synergic effect on the efficiency of estimation and the maximization of profit (e.g., price and promotion elasticity estimation is improved by conducting it within market segments rather than across an entire hetereogeneous population). These estimates are further improved by incorporating “pass through”—a functional relationship between a retailer’s unit prices and unit costs.     

Integrating the collection,fusion, and dissemination of traveler information in Edinburgh,Scotland

The Edinburgh traveler information system, currently being designed for the Edinburgh City Council (ECC), is notable both for its multifaceted approach to the challenges of traffic management in an urban setting and its ability to integrate past, present, and future elements. Integration plays a part in the system design in the following ways:

• •• integration of new and existing systems;
• •• linking together of several disparate systems and procedures;
• •• tight integration of response capabilities with the National Driver Information and Control System (NADICS) operated by the Scottish Office, covering interurban motorways;
• •• incorporation of modularity and flexibility to accommodate future integration.

In describing how the Edinburgh traveler information system is intended to operate, the paper refers to the different types of integration and shows how they are used to benefit the system.The paper begins with a Background outlining the physical, geographical, and institutional context for the system. The Council's environmentally aware policies are referred to, and existing and planned systems, both within and outside Edinburgh, which are relevant to Edinburgh traveler information are briefly described.Following the Background is an overview of the System Design, describing the value added by new elements of the Edinburgh traveler information system and the basic functions to be performed by the system. The Data Collection, Data Fusion, and Data Dissemination aspects of the system are then investigated individually. From the sections describing system structure and operations, it is apparent that the design aims to maximize the collection sources and dissemination mechanisms, but to consolidate the processing of all inputs and outputs in one central location. The system design can accommodate a number of diverse dissemination technologies to ensure that as many target audiences as possible will be exposed to the Information, e.g., variable message signs, remote display terminals, interactive telephone, electronic data exchange, etc.The System Benefits are then outlined and related to the Council policy objectives. The paper ends with a Conclusion and Outlook section which recaps the main points and looks ahead by identifying system enhancements which are anticipated to be integrated in the future.     

Modelling the motion of a three-link manipulator based on a plane with a time-dependent inclination

This work deals with the modelling of a three-link manipulator mounted on a plane with a time-dependent inclination. Two cases are considered.

• (i)The plane is part of a rigid body.
• (ii)The plane is in a moored ship.

     

Multiparametric demand transportation problem

In some applications a minimum cost transportation model arises where supplies are fixed while demands may simultaneously vary. In this paper we analyse the structure of such a model and propose several techniques to describe its behaviour. Our approach is founded on the concept of optimal region, i.e., the subset of demand vectors where a given basic tree is optimal. The proposed algorithm consists in different pivoting strategies designed to:

• 1.build up a minimal list of basic trees such that the associated optimal regions cover the set of feasible demand vectors;
• 2.analyse the effects of either opening a new supplier or closing an existing one;
• 3.suitably treat the dual degenerate case by building up a minimal representation of every maximal region where the optimal value is linear in the demand vector.

Computational complexity is discussed and numerical examples are given.     

An optimal time to sleep for an auto-sleep system considering multi-usage states

An auto-sleep system is defined by the following two properties:

• 1.(i) a call for the system occurs randomly and intermittently
• 2.(ii) the system automatically goes to sleep if there occurs no call during a prespecified time T.

It considers four states:

• 1.(a) sleep
• 2.(b) warm-up
• 3.(c) nonusage
• 4.(d) usage.

For such a system, the time to sleep has been discussed based on suitable criteria. This study extends the model for an auto-sleep system so that the model can deal with multi-usage states. With a view to determining an optimal time to sleep under the extended model, the expected energy consumed per unit time is formulated as a criterion to be minimized. The existence of an optimal time to sleep is examined under a general call distribution. Numerical examples are also provided for a Weibull as well as a log-normal call distribution.     

Free energy and solutions of the Vlasov-Poisson-Fokker-Planck system: external potential and confinement (Large time behavior and steady states)

This paper is devoted to the characterization of external electrostatic potentials for which the Vlasov-Poisson-Fokker-Planck system satisfies one of the following properties:

• (i) the system admits stationary solutions,
• (ii) any solution to the evolution problem converges to a stationary solution, or, equivalently, no mass vanishes for large times,
• (iii) the free energy is bounded from below, We give conditions under which these different notions of confinement are equivalent.

     

Chirurgies d'indice un et isotopies de sphères dans les variétés de contact tendues

We prove the following theorems:

• 1)Any surgery of index one on u tight contact manifold (of dimension three) gives rise to a manifold which carries a natural tight contact structure.
• 2)In a tight contact manifold, any two isotopic spheres which carry the same characteristic foliation are isotopic through a contact isolopy.
• 3)In a tight contact manifold, any two isotopic spheres have isomorphic complements.

     

On degree sequences of undirected,directed, and bidirected graphs

Bidirected graphs generalize directed and undirected graphs in that edges are oriented locally at every node. The natural notion of the degree of a node that takes into account (local) orientations is that of net-degree. In this paper, we extend the following four topics from (un)directed graphs to bidirected graphs:

• –Erdős–Gallai-type results: characterization of net-degree sequences,
• –Havel–Hakimi-type results: complete sets of degree-preserving operations,
• –Extremal degree sequences: characterization of uniquely realizable sequences, and
• –Enumerative aspects: counting formulas for net-degree sequences.

To underline the similarities and differences to their (un)directed counterparts, we briefly survey the undirected setting and we give a thorough account for digraphs with an emphasis on the discrete geometry of degree sequences. In particular, we determine the tight and uniquely realizable degree sequences for directed graphs.     

A simulation of monsoonal cross-equatorial airflow by Lagrangian modelling

The Australian monsoonal cross-equatorial airflow is simulated in an attempt to bridge a highly simplified, while theoretically interesting model to the realities of the actual tropical meteorology. Two factors are found to be essential in the successful simulation of the monsoonal cross-equatorial flow with that model:

• 1.1) the existence of a properly-positioned quasi-elliptic monsoon depression;
• 2.2) sufficient friction to force the decay of anticyclonic inertial oscillations and hence to allow a more ‘balanced’ type of cyclonic flow around that depression.

     

Harmonic Analysis of Neural Networks

It is known that superpositions of ridge functions (single hidden-layer feedforward neural networks) may give good approximations to certain kinds of multivariate functions. It remains unclear, however, how to effectively obtain such approximations. In this paper, we use ideas from harmonic analysis to attack this question. We introduce a special admissibility condition for neural activation functions. The new condition is not satisfied by the sigmoid activation in current use by the neural networks community; instead, our condition requires that the neural activation function be oscillatory. Using an admissible neuron we construct linear transforms which represent quite general functionsfas a superposition of ridge functions. We develop

• • • a continuous transform which satisfies a Parseval-like relation;
• • • a discrete transform which satisfies frame bounds.

Both transforms representfin a stable and effective way. The discrete transform is more challenging to construct and involves an interesting new discretization of time–frequency–direction space in order to obtain frame bounds for functions inL²(A) whereAis a compact set of Rⁿ. Ideas underlying these representations are related to Littlewood–Paley theory, wavelet analysis, and group representation theory.     

An historical reenactment of the battle of Gettysburg on Janus (Army)

Utilizing Janus (A), we analyzed the decision made by LTG Richard Ewell at Gettysburg, PA on the evening of 1 July, 1863. At this time, LTG Ewell decided not to attack Culp's Hill. Instead, he waited until the next morning to attack, to permit the mustering of both artillery support and his third division, under command of MG Johnson. Many historians contend that this was a poor tactical decision and was a direct cause of the confederate loss at Gettysburg and possibly the war. We have investigated this issue using a combat simulation model called Janus (Army).Prerequisite to the simulation, systems and weapons of the time had to be modeled in the Janus database. To keep this relatively manageable, we decided to model only the most significant system types on each side. These included the Confederate and Yankee soldier armed with a bayonet and a non-repeating rifle; the cannoneer and cannon (12 Ib ball and cannister-shot) on each side. In total, the simulation represented nearly 200,000 systems engaged at Gettysburg.Our study employed a two level, two factor experimental design. The two factors were the presence of the corp's artillery and Johnson's division. Both factors were relevant to the decision to delay the confederate attack. The levels corresponded with whether or not each factor was used in the simulation. In all, we conducted three replications of the following four design points (tactical alternatives) from which to base our conclusions:

• 1.Design Point 1 (B): Situation on 1 Jul 1863 (no change). Ewell's Corps attacks.
• 2.Design Point 2 (B+A): Corps Artillery supports the attack.
• 3.Design Point 3 (B+J): MG Johnson's Division participates in attack.
• 4.Design Point 4 (B+A+J): Corps Artillery supports and MG Johnson's Division participates in attack.We conclude that LTG Ewell made the correct tactical decision. Without either his corps artillery or Johnson's Division, the corps would have faced annihilation should he have attacked on 1 July. Had he had his corps artillery (6 guns), he probably should have pushed aggressively up the hill. If he had only Johnson's division, he probably could have taken the hill but could not have held it as a tenable position for very long.

     

Probabilistic inequalities and remarks

The authors use their recently proved integral inequality to obtain bounds for the covariance of two random variables

• 1.in a general setup and
• 2.for a class of special joint distributions.

The same inequality is also used to estimate the difference of the expectations of two random variables. Finally, the authors study the attainability of a related inequality.     

Dynamic graph models

Research in graph theory has focused on studying the structure of graphs with the assumption that they are static. However, in many applications, the graphs that arise change with time, i.e., they are dynamic in nature. This is especially true of applications involving graph models in computer science. We present an expository study of dynamic graphs with the main driving force being practical applications. We first develop a formal classification of dynamic graphs. This taxonomy in the form of generalizations and extensions will in turn suggest new areas of application. Next, we discuss areas where dynamic graphs arise in computer science such as compilers, databases, fault-tolerance, artificial intelligence, and computer networks. Finally, we propose approaches that can be used for studying dynamic graphs. The main objective in any study of dynamic graphs should be to

• 1.(i) extend results developed for static graph theory to dynamic graphs,
• 2.(ii) study the properties that describe how a dynamic graph changes,
• 3.(iii) investigate problems and issues in dynamic graph theory that are raised by practical applications of dynamic graphs in computer science.