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We consider a simplification of a typical university course timetabling problem involving three types of hard and three types of soft constraints. A MAX-MIN Ant System, which makes use of a separate local search routine, is proposed for tackling this ...

We present a MAX-MIN Ant System for the Group Shop Scheduling problem and propose several extensions aiming for a more effective intensification and diversification of the search process. Group Shop Scheduling is a general Shop Scheduling problem ...

We investigate a multi-agent algorithm inspired by the task allocation behavior of social insects for the solution of dynamic task allocation problems in stochastic environments. The problems consist of a certain number of machines and different kinds ...

The prediction of a protein's conformation from its aminoacid sequence is one of the most prominent problems in computational biology. Here, we focus on a widely studied abstraction of this problem, the two dimensional hydrophobic-polar (2D HP) protein ...

The Vehicle Routing Problem with Time Windows (VRPTW) involves scheduling and routing of a vehicle fleet to serve a given set of geographically distributed requests, subject to capacity and time constraints. This problem is encountered in a variety of ...

The present work is focused on the assembly line balancing design problems whose objective is to minimize the number of stations needed to manufacture a product in a line given a fixed cycle time, equivalent to a fixed production rate. The problem is ...

This paper proposes a new framework for the optimization of logistic processes using ant colonies. The application of the method to real data does not allow to test different parameter settings on a trial and error basis. Therefore, a sensitive analysis ...

In this paper we present a new Ants System approach to a dynamic Travelling Salesman Problem. Here the travel times between the cities are subject to change. To handle this dynamism several ways of adapting the pheromone matrix both locally and globally ...

Many animals use chemical substances known as pheromones to induce behavioural changes in other members of the same species. The use of pheromones by ants in particular has lead to the development of a number of computational analogues of ant colony ...

Population based ACO algorithms for dynamic optimization problems are studied in this paper. In the population based approach a set of solutions is transferred from one iteration of the algorithm to the next instead of transferring pheromone information ...

Finding paths in networks is a well exercised activity both in theory and practice but still remains a challenge when the search domain is a dynamic communication network environment with changing traffic patterns and network topology. To enforce ...

In this paper we present and analyze the application of an Ant System to the Vehicle Routing Problem with Backhauls and Time Windows (VRPBTW). At the core of the algorithm we use an Insertion procedure to construct solutions. We provide results on the ...

The behaviour of Ant Colony Optimization (ACO) algorithms is studied on optimization problems that are composed of different types of subproblems. Numerically exact results are derived using a deterministic model for ACO that is based on the average ...

In this paper we describe an individual-based model to account for the growth and morphogenesis of networks of galleries in the ant Messor sancta. The activity of the individuals depends only on their local perception of the immediate surroundings. ...

The Probabilistic Traveling Salesman Problem (PTSP) is a TSP problem in which each customer has a given probability of requiring a visit. The goal is to find an a priori tour of minimal expected length over all customers, with the strategy of visiting a ...

This paper develops the formal framework of ant programming with the goal of gaining a deeper understanding on ant colony optimization and, more in general, on the principles underlying the use of an iterated Monte Carlo approach for the multi-stage ...

We study robots that leave trails in the terrain to cover closed terrain efficiently and robustly. Such ant robots have so far been studied only theoretically for gross ant robot simplifications in unrealistic settings. In this article, we design ant ...

Ant colony algorithms are a class of metaheuristics which are inspired from the behaviour of real ants. The original idea consisted in simulating the trail communication, therefore these algorithms are considered as a form of adaptive memory ...

Metaheuristics in general and ant-based systems in particular have shown remarkable success in solving combinatorial optimization problems. However, a few problems exist for which the best performing heuristic algorithm is not a metaheuristic. These few ...

In this contribution, we will study the influence of the three components of the Best-Worst Ant System (BWAS) algorithm. As the importance of each of them as the fact whether all of them are necessary will be analyzed. Besides, we will introduce a new ...

The question of routing loop formation is examined for a class of routing schemes based on "agents" or "ants". First the notion of loop existence is discussed for the general case of routing tables with multiple, weighted entries. A simple criterion is ...

Ant Colony Optimisation based solvers systematically scan the set of possible solution elements before choosing a particular one. Hence, the computational time required for each step of the algorithm can be large. One way to overcome this is to limit ...

This study considers the routing and wavelength assignment problem (RWA) in optical wavelength-division-multiplexed networks. The focus is dynamic traffic, in which the number of wavelengths per fiber is fixed. We minimize connection blocking using an ...

The self-organizing and autonomous behavior of social insects such as ants presents an interesting and powerful metaphor for applications in the retrieval and management of large and fast growing amount of online information. The explosive growth of web ...

The Set Covering Problem (SCP) represents an important class of NP-hard combinatorial optimization problems. Actually, the exact algorithms, such as branch and bound, don't find optimal solutions within a reasonable amount of time, except for small ...

Manufacturing Control Problems are still often solved by manual scheduling, that means only out of the workers experience. Modern algorithms, such as Ant Colony Optimization, have proved their capacity to solve this kind of problems. Nevertheless, they ...

The scouts of Leptothorax albipennis colonies find and assess new nest sites, when their current nests become uninhabitable. Observations of these scouts have suggested that they assess, among other things, the integrity of the internal periphery and ...

We propose the addition of Genetic Algorithms to Ant Colony System (ACS) applied to improve performance. Two modifications are proposed and tested. The first algorithm is a hybrid between ACS-TSP and a Genetic Algorithm that encodes experimental ...