Chocolate P Automata -- Solving the N-Queens Puzzle by Using Few Membranes -- Model of Antibiotic Resistance Evolution Dynamics Through P Systems with Active Membranes and Communication Rules -- Small Spiking Neural P Systems with Structural Plasticity -- Approximating Polygons for Space-Filling Curves Generated with P Systems -- A Logical Representation of P Colonies: An Introduction -- The Fair Proportion is a Shapley Value on Phylogenetic Networks Too -- Deterministic Parsing with P Colony Automata -- ACORD: Ant Colony Optimization and BNF Grammar Rule Derivation -- Membrane Computing as a Modeling Tool: Looking Back and Forward from Seville -- Identifiable Kernel P Systems -- Other Buds in Membrane Computing -- The Java Environment for Nature-Inspired Approaches (JENA): A Workbench for Bio-Computing and Bio-Modeling Enthusiasts -- WEBRSIM: A Web-Based Reaction Systems Simulator -- Open Problems in Membrane Computing and How Not to Solve Them -- A Note on the Entropy of .-An Introduction to cP Systems -- A Look at the Descriptional Complexity of SNQ P Systems -- Design Patterns for Efficient Solutions to NP-Complete Problems in Membrane Computing -- Spiking Neural P Systems: Theoretical Results and Applications -- Aggregating Parallel Multi-set Rewriting Systems -- On Languages Generated by Context-Free Matrix Insertion-Deletion Systems with Exo-Operations -- A Simulation Workflow for Membrane Computing: from MeCoSim to PMCGPU Through P-Lingua -- An Implementation of Elementary Arithmetic with Virus Machine -- A Kernel-Based Membrane Clustering Algorithm. .

This Festschrift is in honor of Mario de Jesús Pérez-Jiménez, Professor in the Department of Computer Science of University of Seville, Spain, on the occasion of his 70th birthday. The title of this volume reflects both his main research area, viz., Natural Computing, and the guiding principle of his functioning: "once you choose to do something, enjoy doing it". The respect that Professor Mario de Jesús Pérez-Jiménez enjoys in the scientific community was well demonstrated by the enthusiastic response received to the request to contribute to this book. The contributions by more than 70 authors from 15 countries cover a wide spectrum of research areas and reflect well the broad range of research interests of Professor Mario de Jesús Pérez-Jiménez. The research areas presented in this Festschrift include membrane computing, spiking neural networks, phylogenetic networks, ant colonies optimization, workbench for biocomputing, reaction systems, entropy of computation, rewriting systems, and insertion-deletion systems.