Gara Miranda Valladares

• Doctora en Informática
• Professor at University of La Laguna

The way heuristic optimizers are designed has evolved over the decades, as computing power has increased. Such has been the case for the linear ordering problem (LOP), a field in which trajectory-based strategies led the way during the 1990 s, but which have now been surpassed by memetic schemes. This paper focuses on understanding how the design o...

RoblockLLy is an Educational Robotics simulator designed for primary and secondary school students whose goal is to increase their interest in STEM. In the particular case of Computer Science, it allows developing Computational Thinking skills. It has been designed with ease of use in mind. This free tool is available through a web browser and does...

This document describes MAEDM-OCM, a first generation memetic algorithm for the one-sided crossing minimization problem (OCM), which obtained the first position at the heuristic track of the Parameterized Algorithms and Computational Experiments Challenge 2024. In this variant of OCM, given a bipartite graph with vertices V = A ∪ B, only the nodes...

The way heuristic optimizers are designed has evolved over the decades, as computing power has increased. Initially, trajectory metaheuristics used to shape the state of the art in many problems, whereas today, population-based mechanisms tend to be more effective. Such has been the case for the Linear Ordering Problem (LOP), a field in which strat...

This article examines the effectiveness and interest generated among primary and secondary education students through activities aimed at developing Computational Thinking skills, in the context of the coronavirus disease 2019 pandemic. The shift to online or hybrid learning models posed a significant challenge for educators, particularly those lac...

Emotions are essential drivers of the learning process, influencing motivation, performance, and problem-solving abilities. In the field of Computer Science, students often struggle with negative emotions during programming activities, impacting their performance and project quality. To address this challenge, there is a growing need to introduce C...

La última reforma educativa de nuestro país incorpora entre sus competencias la resolución de problemas a través del pensamiento computacional. Esto supone un cambio de paradigma a nivel formativo: las personas no serán meras usuarias de la tecnología sino que, desde jóvenes, adquirirán habilidades para ser creadoras y desarrolladoras en este mundo...

Emotions affect how we acquire knowledge, being one of the causes of the demotivation generated at the time of studying a new field. Computer Science does not always pique the interest of young people, so we carry out an analysis of emotions that are present in primary and secondary school students, around 8-9 years old and 12-13 years old, who eng...

En 2016, se puso en marcha el Aula Cultural de Pensamiento Computacional de la Universidad de La Laguna para dar respuesta social a la confusión que surge al integrar las Tecnologías de la Información y las Comunicaciones en la educación. Es importante distinguir entre los términos “Alfabetización Digital”, “Pensamiento Computacional” y “Ciencias d...

En este trabajo se presenta una actividad de aprendizaje-servicio para una asignatura del Grado en Ingeniería Informática en la que se estudian lenguajes y paradigmas de programación. La actividad, de carácter voluntario, consiste en diseñar y ejecutar un ejercicio que permita promocionar entre los jóvenes las Ciencias de la Computación mediante el...

The Linear Ordering Problem (LOP) is a very popular NP-hard combinatorial optimization problem with many practical applications that may require the use of large instances. The Linear Ordering Library (LOLIB) gathers a set of standard benchmarks that are widely used in validating solvers for the LOP. Among them, xLOLIB2 collects some of the largest...

Computational thinking could be described as the thought processes involved in formulating problems and representing their solutions in such a way that these solutions can be executed by an information processing agent (either a human, a computer, or combinations of both). Therefore, this process involves learning to think about how to represent an...

Although Computer Science has grown to become one of the most highly demanded professional careers, every year, only a small percentage of students choose a degree directly related to Computer Science. Perhaps the problem lies in the lack of information that society has about Computer Science itself, and particularly about the work computer scienti...

The publication with new fetures is in: https://doi.org/10.1007/s12293-022-00378-5 The Linear Ordering Problem (LOP) is a very popular NP-hard combinatorial optimization problem with many practical applications that may require the use of large instances. The Linear Ordering Library (LOLIB) gathers a set of standard benchmarks widely used in the...

This paper presents a study of the emotions that are produced in pre-university students when performing Computational Thinking activities. Two strategies are compared in which the guided and discovery methodologies are interspersed. It is concluded that positive and ambiguous emotions are mainly produced, while negative ones have relatively low in...

This paper presents a study of the emotions that are produced in pre-university students when performing Computational Thinking activities. In the absence of an official document that deals what content of Computational Thinking should be taught at the national level, we carefully selected a set of activities called Piens@ Computacion@ULLmente, tha...

This work presents a curricular proposal of activities to include computational thinking skills in pre-university studies for students from 8-9 years old and 12-13 years old. This proposal is made for two modalities, one guided and the other by discovery, in which the development of solutions to different problems is proposed by designing an algori...

A multi-objective formulation of the Menu Planning Problem, which is termed the Multi-objective Menu Planning Problem, is presented herein. Menu planning is of great interest in the health field due to the importance of proper nutrition in today’s society, and particularly, in school canteens. In addition to considering the cost of the meal plan as...

One of the main components of most modern Multi-Objective Evolutionary Algorithms (MOEAs) is to maintain a proper diversity within a population in order to avoid the premature convergence problem. Due to this implicit feature that most MOEAs share, their application for Single-Objective Optimization (SO) might be helpful, and provides a promising f...

SCHOOLTHY: Automatic Menu Planner for Healthy and Balanced School Meals is a decision support tool that addresses the multi-objective menu planning problem in order to automatically produce meal plans for school canteens. Malnutrition is a widespread problem nowadays and is particularly serious when it affects children. In our environment, nutritio...

The transformation of traditional education into a Sensitive, Manageable, Adaptable, Responsive and Timely (SMART) education involves the comprehensive modernisation of all educational processes. For such a transformation, smart pedagogies are needed as a methodological issue while smart learning environments represent the technological issue, both...

Most Multi-objective Evolutionary Algorithms (MOEAs) operate without explicitly promoting the diversity of the variable space. Nevertheless, in the single-objective domain it has been shown that properly managing this kind of diversity might lead to higher-quality solutions. In this paper the diversity of the variable space is analyzed for several...

Container Loading Problems (CLPs) deal with determination of the optimal pattern for packing boxes into a given container usually with respect to the maximal utilization of the total container volume. On the other hand, it is also important to maximize the utilization of the maximal container weight for which is paid when buying a shipment service....

3D cutting and packing problems have important applications and are of particular relevance to the transportation of cargo in the form of Container Loading Problems (CLP). Many algorithms have been proposed for solving the 2D/3D cutting stock problems but most of them consider single objective optimization. The goal of the problem is to load the bo...

Cutting and packing problems have important applications to the transportation of cargo. Many algorithms have been proposed for solving the 2D/3D cutting stock problems but most of them consider single objective optimization. The goal of the problem here proposed is to load the boxes that would provide the highest total volume and weight to the con...

Core subjects by field of knowledge for official University studies have been established in Annex II of the RD 1393/2007. Computer Science appears only in Engineering and Architecture Degrees. It is therefore necessary that the training received by high school students in the Computer field is not limited only to the intrinsic knowledge of current...

In recent decades, several multi-objective evolutionary algorithms have been successfully applied to a wide variety of multi-objective optimization problems. Along the way, several new concepts, paradigms and methods have emerged. Additionally, some authors have claimed that the application of multi-objective approaches might be useful even in sing...

This paper presents a Graphical User Interface for a service used to solve the Container Loading Problem as applied to the logistic industry, commonly encountered in transportation and wholesaling industries. This interface allows users to see how items (boxes) are to be placed in the container. In order to decide where exactly to locate each item,...

This work deals with a multi-objective formulation of the Container Loading Problem which is commonly encountered in transportation and wholesaling industries. The goal of the problem is to load the items (boxes) that would provide the highest total volume and weight to the container, without exceeding the container limits. These two objectives are...

In recent decades, several multi-objective evolutionary algorithms have been successfully applied to a wide variety of multi-objective optimization problems. Along the way, several new concepts, paradigms and methods have emerged. Additionally, some authors have claimed that the application of multi-objective approaches might be useful even in sing...

The maintenance of a proper diversity is an important issue for the correct behavior of Evolutionary Algorithms (EAs). The loss of diversity might lead to stagnation in suboptimal regions, producing the effect known as “premature convergence”. Several methods to avoid premature convergence have been previously proposed. Among them, the use of Multi...

This work presents a multi-objective approach to solve the Container Loading Problem. The single-objective formulation of the problem has been widely studied in the related literature, trying to optimise the total volume of the packed pieces into the container. However, a rather common aspect in the scope of this problem is the weight limit of the...

This work introduces several improvements in the solution of the Constrained 2D Cutting Problem. Such improvements combine the detection of dominated and duplicated cutting patterns with the implementation of parallel approaches for best-first search methods. The analysis of symmetries and dominances among the cutting patterns is able to discard so...

Most research on Strip Packing and Cutting Stock problems are focused on single-objective formulations of the problems. However, in this work we deal with more general and practical variants of the problems, which not only seeks to optimise the usage of the raw material, but also the overall production process.The problems target the cutting of a l...

This work presents a multi-objective approach to solve a Constrained Guillotine Two-Dimensional Cutting Stock Problem. The single-objective formulation of the problem has been widely studied in the related literature, so a large number of heuristics, meta-heuristics, and exact algorithms have been proposed in order to optimise the total profit obta...

In this paper, a tool for simulating the impulse response for indoor wireless optical channels using 3D computer-aided design (CAD) models is presented. The tool uses a simulation algorithm that relies on ray tracing techniques and the Monte Carlo method and improves on all previous methods from a computational standpoint. The 3D scene, or the simu...

This work presents a set of approaches used to deal with the frequency assignment problem (FAP), which is one of the key issues in the design of GSM networks. The used formulation of FAP is focused on aspects which are relevant for real-world GSM networks. A memetic algorithm, together with the specifically designed local search and variation opera...

This work presents a multi-objective approach to solve the Constrained 2D Cutting Stock Problem. The problem targets the cutting of a large rectangle of fixed dimensions in a set of smaller rectangles using orthogonal guillotine cuts. Although the problem is usually focused on a single objective, in this work we want to optimise the layout of recta...

Antenna Positioning Problem (app) is an NP-Complete Optimisation Problem which arises in the telecommunication field. It consists in identifying the infrastructures required to establish a wireless network. Several objectives must be considered when tackling app: minimise the cost, and maximise the coverage, among others. Most of the proposals simp...

Most research on Strip Packing Problems is focused on the single-objective formulation of the problem. However, in this work we deal with a more general and practical variant of the problem, which not only seeks to optimize the usage of the raw material, but also the production process. For the problem solution, we have applied some of the most-kno...

Nowadays, mobile communications are experiencing a strong growth, being more and more indispensable. One of the key issues in the design of mobile networks is the frequency assignment problem (FAP). This problem is crucial at present and will remain important in the foreseeable future. Real-world instances of FAP typically involve very large networ...

This work analyses two different approaches to parallelise an exact algorithm for the solution of the Constrained Two-Dimensional Cutting Stock Problem. A fine-grained model based on the parallel execution of the generation loops is implemented through a shared-memory model using the OpenMP tool. Also, a coarse-grained model based on the parallel e...

Antenna Positioning Problem (app) is an NP-Complete Optimisation Problem which arises in the telecommunication field. It consists in identifying the infrastructures required to establish a wireless network. Several objectives must be considered when tackling app and multi-objective evolutionary algorithms have been successfully applied to solve it....

The radio network design (RND) is an NP-hard optimization problem which consists of the maximization of the coverage of a given area while minimizing the base station deployment. Solving RND problems efficiently is relevant to many fields of application and has a direct impact in the engineering, telecommunication, scientific, and industrial areas....

This paper presents a parallel framework for the solution of multi-objective optimization problems. The framework implements some of the best known multi-objective evolutionary algorithms. The plugin-based architecture of the framework minimizes the end user effort required to incorporate their own problems and evolutionary algorithms, and facilita...

This work presents several approaches used to deal with the 2D packing problem proposed in the GECCO 2008 contest session. A memetic algorithm, together with the specifically designed local search and variation operators, are presented. A novel parallel model was used to parallelize the approach. The model is a hybrid algorithm which combines a par...

This work presents a set of improvements and a performance analysis for a previously designed multi-objective optimisation parallel model. The model is a hybrid algorithm that combines a parallel island-based scheme with a hyperheuristic approach in order to grant more computational resources to those schemes that show a more promising behaviour....

This work presents the application of a parallel cooperative optimization approach to the broadcast operation in mobile ad-hoc networks (manets). The optimization of the broadcast operation implies satisfying several objectives simultaneously, so a multi-objective approach has been designed. The optimization lies on searching the best configuration...

In this work, an exact approach to solve the Error Correcting Code problem is presented. For the implementation, the Branch and Bound skeleton of the MaLLBa library has been applied. This tool provides a hierarchy of C++ classes which must be adapted to the specific requirements of the problem. Then, it generates two parallel solvers: one based on...

This paper considers a real-world two-dimensional strip packing problem involving specific machinery constraints and actual cutting production industry requirements. To adapt the problem to a wider range of machinery characteristics, the design objective considers the minimisation of material length and the total number of cuts for guillotinable-ty...

ULL::A-Team tool is a library that provides a skeleton to solve multi-objective optimization problems by applying evolutionary algorithms. In addition to providing sequential implementations of some of the best-known evolutionary algorithms, the skeleton provides great flexibility in obtaining parallel schemes. This flexibility is achieved by speci...

This work presents an optimization approach for the broadcast operation in MANETs based on the DFCN protocol. Such approach involves a multi-objective optimization that has been tackled through the cooperation of a team of evolutionary algorithms. The proposed optimization model is a hybrid algorithm that combines a parallel island-based scheme wit...

This work presents a new parallel model for the solution of multi-objective optimization problems. The model combines a parallel island-based scheme with a hyperheuristic approach in order to raise the level of generality at which most current evolutionary algorithms operate. This way, a wider range of problems can be tackled since the strengths of...

The Frequency Assignment Problem (FAP) is one of the key issues in the design of GSM networks (Global System for Mobile communications), and will remain important in the foreseeable future. There are many versions of FAP, most of them benchmarking-like problems. We use a formulation of FAP, developed in published work, that focuses on aspects which...

Introduction Top-Down Approach Bottom-Up Approach Automata Theory and Dynamic Programming Parallel Algorithms Dynamic Programming Heuristics Conclusions References

This work analyses the difficulties of parallelizing the best known sequential algorithm for the 2D cutting stock problem. All the approaches to parallelize the algorithm strive against its highly irregular computation structure and its sequential nature. A distributed-memory parallel algorithm has been designed through a time-driven task intercomm...

This paper presents the graphical user interface (GUI) for a remote service used to solve the 2D guillotine cutting stock problem as applied to the textile industry. This interface allows for the patterns in the regional dress of the city of La Orotava, in the Canary Islands, to be defined and manipulated. The user chooses the garment, quantity and...

This work presents a new parallel model for the solution of multi-objective optimization problems. The model is based on the cooperation of a set of evolutionary algorithms. The main aim is to raise the level of generality at which most current evolutionary algorithms operate. This way, a wider range of problems can be tackled since the strengths o...

This work presents a parallel framework for the solution of multi-objective optimization problems. The framework implements some of the best known multi-objective evolutionary algorithms. The framework architecture makes usage of configuration files to provide a more extensive and simple customization environment than other similar tools. A wide va...

11th International Conference on Computer Aided Systems Theory. Las Palmas de Gran Canaria, Spain, February 12-16, 2007 Mobile Ad-hoc Networks (MANETs) are composed of a set of communicating devices which are able to spontaneously interconnect without any pre-existing infrastructure. In such scenario, broadcasting becomes an operation of tremendous...

This work introduces a set of important improvements in the resolution of the Two Dimensional Cutting Stock Problem. It presents a new heuristic enhancing existing ones, an original upper bound that lowers the upper bounds in the literature, and a parallel algorithm for distributed memory machines that achieves linear speedup. Many components of th...

Many real-world problems are based on the optimization of more than one objective function. This work presents a tool for the resolution of multi-objective optimization problems based on the cooperation of a set of algorithms. The invested time in the resolution is decreased by means of a parallel implementation of an evolutionary team algorithm. T...

This work presents a new approach to optimize the broadcast operation in manets based on a team of evolutionary algorithms. A library of parallel algorithmic skeleton for the resolution of multi-objective optimization problems has been applied. This tool provides a C++ implementation of a selection of the literature best-known evolutionary multi-ob...

Mobile Ad-hoc Networks (MANETs) are composed of a set of communicating devices which are able to spontaneously interconnect without any pre-existing infrastructure. In such scenario, broadcasting becomes an operation of tremendous importance for the own existence and operation of the network. Optimizing a broadcasting strategy in MANETs is a multio...

This work presents a skeleton for the resolution of multi-objective optimization problems using the improved version of the strength Pareto evolutionary algorithm (SPEA2). From the same problem specification, the skeleton derives sequential and distributed parallel solvers. The user interface for the problem definition consists of a set of classes...

Resumen En este trabajo se presenta una propuesta de prácticas de laboratorio para el tema de Invocación de Métodos Remotos utilizando el lenguaje de programación Java, en el contexto de una asignatura de Programación de Sistemas Distribuidos. En primer lugar, se propone una práctica de iniciación al modo de uso y a continuación, la implementación...

Cutting Stock Problems (CSP) arise in many production industries where large stock sheets must be cut into smaller pieces. We present a parallel algorithm – based on Viswanathan and Bagchi algorithm (VB) – solving the Two-Dimensional Cutting Stock Problem (2DCSP). The algorithm guarantees the processing of best nodes first and does not introduce an...

This work presents a skeleton for the resolution of optimization problems using general tree search techniques. This skeleton provides to the user a sequential solver and a parallel solver based on the shared memory paradigm. The user interface for the specification of the necessary classes and methods is described. Also the internal operation mode...

Cutting stock problems arise in many industries where large stock sheets of a given material must be cut into smaller pieces. Many algorithms have been proposed for solving each of the problem formulations. We present different implementations based on Viswanathan and Bagchi's algorithm to solve the two-dimensional cutting stock problem (2DCSP). On...

This work presents a skeleton for the A* heuristic search. This skeleton provides to the user a sequential solver and a parallel solver based in the shared memory paradigm. The user interface for the specification of the necessary classes and methods to solve an specific problem is described. Also the internal operation mode of the two solvers is...

Resumen. Este artículo presenta una interfaz gráfica de usuario para la resolución del problema de corte bidimendional. Es sistema está aplicado a la industria textil, permitiendo la definición y manipulación de los patrones que componen el traje tradicional de las Islas Canarias. A través de los menús, el usuario ha de seleccionar la prenda que qu...