Algorithms and data structures for hierarchical memories

The memories of real life computers usually have a hierarchical structure with levels like registers, cache, main memory and disks. In contrast, the RAM model is based on a homogeneous memory, hence hidding an important source for speeding up programs, their locality. Locality means that algorithms can be implemented to run the faster the better they are adapted to mechanisms like blocking data or keeping currently used data in fast levels. We describe a model (MDMH) which reflects the most important features of computer memories and is despite of easy enough to design and analyse algorithms. We give MDMH algorithms for basic problems, e.g. maintaining heaps and sorting. Most of them can be proved to be optimal according to a modified measure of asymptotic complexity. Finally, we introduce a parallel version of MDMH modelling memory banks (MDMHP) and describe a general method for translating MDMH algorithms to MDMHP. (orig.)SIGLEAvailable from TIB Hannover: RR 2036(17) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

On the power of meta-interpretation and partial evaluation in logic programming

Meta-interpretation and partial evaluation are considered to be two powerful techniques in artificial intelligence programming. Metainterpretation is rather flexible in treating programs as data. On the other hand, metainterpretation has a decisive disadvantage: its efficiency. Partial evaluation was used to remove the overhead of meta-programming by specializing the meta-program with respect to a given input to which the meta-program has to be applied. We implemented both meta-interpretation and partial evaluation in a comparably large system, an expertsystem shell based on logic programming. The major result was surprizing: In a more realistic application, meta-interpretation is much more powerful with respect to efficiency than expected. (orig.)SIGLEAvailable from TIB Hannover: RR 2036(15) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Declarative semantics for changing objects A metaprogramming approach

Dynamical and object-structured knowledge bases are assigned a logical ('declarative') semantics in terms of logical metaprogramming. Built-in procedures for manipulating the object-structured database are defined by meta-level predicates. (orig.)Available from TIB Hannover: RR 2036(9) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Structure and importance of logspace-MOD-classes

We refine the techniques of Beigel, Gill, Hertrampf (BGH90) who investigated polynomial time counting classes, in order to make them applicable to the case of logarithmic space. We define the complexity classes MOD_kL and demonstrate their significance by proving that all standard problems of linear algebra over the finite rings Z/kZ are complete for these classes. We then define new complexity classes LogFew and LogFewNL and identify them as adequate logspace versions of Few and FewP. We show that LogFewNL is contained in MODZ_kL and that LogFew is contained in MOD_kL for all k. Also an upper bound for L"L in terms of computation of integer determinants is given from which we conclude that all logspace counting classes are contained in NC"2. (orig.)Available from TIB Hannover: RR 2036(5) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Dialogue acts in automatic dialogue interpreting

In this paper we demonstrate that for an adequate translation of an utterance spoken in a dialogue the dialogue act it performs has to be determined. We introduce an approach that automatically assigns types of dialogue acts to utterances on the basis of both micro- and macro-structural information. Technically, this assignment is realized by modeling preference rules as weighted defaults in the Description Logic system FLEX. The dialogue-act type of an utterance is determined by qualitatively minimizing the exceptions to these defaults. The results described here have been developed within the Verbmobil project, a project concerned with face-to-face dialogue interpreting funded by the German Federal Ministry of Education, Science, Research and Technology (BMBF). We present the rather positive results of a first evaluation of this implementation showing the accuracy of dialogue act assignment. (orig.)SIGLEAvailable from TIB Hannover: RR 5221(173)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Objektorientierte Prozesssimulation in C++

Es wird gezeigt, wie in C++ ein weitgehend portables Prozesskonzept unter Nutzung von Klassen entwickelt werden kann, das es unter anderem gestattet, neben einer Simulationsbibliothek fuer zeitdiskrete Prozessmodelle auch eine Simulationsbibliothek fuer zeitkontinuierliche Prozessmodelle aufzubauen und diese beiden darueber hinaus unproblematisch miteinander zu kombinieren. Damit koennen Prozessmodelle simulativ untersucht werden, die durch kooperierende zeitdiskrete und zeitkontinuierliche Prozesse charakterisiert sind. Insbesondere werden verschiedene Synchronisationsformen beider Prozessarten unterstuetzt. Durch ein umfangreiches Angebot an Trace- und statistischer Reportprotokolle, eignen sich die Bibliotheken insbesondere fuer eine Modellierungs- und Simulationsausbildung unterschiedlichster Fachgebiete. (orig.)SIGLEAvailable from TIB Hannover: RR 2036(14) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Dynamic point location in general subdivisions

The dynamic planar point location problem is the task of maintaining a dynamic set S of n non-intersecting, except possibly at endpoints, line segments in the plane under the following operations: Locate (q: point): Report the segment immediately above q, i.e., the first segment intersected by an upward vertical ray starting at q; Insert (s: segment): Add segment s to the collection of S of segments; Delete (s: segment): Remove segment s from the collectection S of segments. We present a solution which requires space O(n), has query and insertion time O(log n log log n) and deletion time O(log"2n). A query below O(log"2n) was previously only known for monotone subdivisions and horizontal segments and required non-linear space. (orig.)SIGLEAvailable from TIB Hannover: RR 2036(16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Multicriterial fractional optimization

At first we introduce different solution concepts for general vector optimization problems and summarize some relations between them. Further, we apply these solution concepts to vectorial fractional optimization problems and show that the well-known Dinkelbach-transformation can be generalized in the sense, that even in vector optimization excact as well as approximate solutions for the original problem and for th transformed one are closely related. Finally, we discuss possibilities to handle the transformed vector optimization problem by means of parametric optimization. (orig.)Available from TIB Hannover: RR 6329(96-13) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Algorithmic learning for knowledge-based systems. Pt. 1 Final report

The investigations within the joint research project GOSLER have been focussed on theoretical problems of learning from usually incomplete information (so-called inductive inference). This research has been motivated by the underlying assumption that knowledge-based systems' applications in complex domains are normally faced to the problem of vagueness and incompleteness of information both about the system or installation considered and the dynamic processes maintained. Among the main inference mechanisms of knowledge-based systems, inductive inference will usually play some key role. The joined project yields some considerable contribution to the theory of inductive inference. The research focussed mainly on theoretical results and prototypical implementations. The main emphasis of the research efforts was put on special effects in inductive inference (like inconsistent hypothesis formation, for instance) which are not yet taken into consideration and implemented in most of the recent knowledge-based systems in use. The theoretical results have been validated and applied by building prototypical systems like T_LP"S and GOSLERP. T_LP"S is an interactive system for design and testing of rewrite systems. GOSLERP is based on the logic programming paradigm with the emphasis on certain metaprogramming features (backtracking of assert and retract). GOSLERP is particularly taylored towards the creation of learning modules for knowledge-based systems. (orig.)Available from TIB Hannover: F95B1492+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Regularized penalty methods for optimal control of ill-posed elliptic systems

Application of prox-regularization to ill-posed stationary control problems is investigated. Stable variants of penalty methods with one-step and multi-step regularizations in the auxiliary problems are developed and their convergence is proved for distributed as well as boundary control problems with state constraints and Dirichlet or Neumann conditions. (orig.)SIGLEAvailable from TIB Hannover: RO 7722(522) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman