The topic of this thesis is established in the area of mathematical cryptology, more preciselyin group based cryptology. We give extensions of cryptographic protocols, develop new crypto-graphic protocols concerning the mathematical background and give modifications of them. Inaddition cryptographic analysis as well as examples are given. The focus lays on the developmentof new ...

Auctions and exchanges are important coordination mechanisms for multiagent systems. Most multi-good markets are combinatorial in that the agents have preferences over bundles of goods. We study the possibility of determining prices so as to support (efficient) allocations in combinatorial economies where a seller (or arbitrator) wants to implement an efficient allocation. Conditions on the exi...

Systematic change of neighborhood within a possibly randomized local search algorithm yields a simple and e€ective metaheuristic for combinatorial and global optimization, called variable neighborhood search (VNS). We present a basic scheme for this purpose, which can easily be implemented using any local search algorithm as a subroutine. Its e€ectiveness is illustrated by solving several class...

We introduce a novel paradigm for creating musical objects, based on the combination of a machine-learning and a combinatorial algorithm. In this scheme users associate freely subjective descriptions (tags) to musical objects. A machine-learning component continuously learns a mapping between these tags and a set of technical features. Thanks to a combinatorial generator, the user can then reus...

In this paper we show the combinatorial structure of Z modulo sublattices selfsimilar to Z. The tool we use for dealing with this purpose is the notion of association scheme. We classify when the scheme defined by the lattice is imprimitive and characterize its decomposition in terms of the decomposition of the gaussian integer defining the lattice. This arise in the classification of different...

We propose an algorithm for combinatorial optimization where an explicit check for the repetition of configurations is added to the basic scheme of Tabu search. In our Tabu scheme the appropriate size of the list is learned in an automated way by reacting to the occurrence of cycles. In addition, if the search appears to be repeating an excessive number of solutions excessively often, then the ...

This article proposes efficient solutions for the construction of sealed-bid second-price and combinatorial auction protocols in an active adversary setting. The main reason for constructing secure auction protocols is that the losing bids can be used in the future auctions as well as negotiations if they are not kept private. Our motivation is to apply verifiable secret sharing in order to con...

Focusing on the generation mechanism of random permutation solutions, this paper investigates the application of the Simulated Annealing (SA) algorithm to the combinatorial optimisation problems with permutation property. Six types of perturbation scheme for generating random permutation solutions are introduced. They are proved to satisfy the asymptotical convergence requirements. The results ...