In this thesis, we introduce action probabilistic (ap-) logic programs, a formalism for reasoning about the probability of events whose inter-dependencies are not known. Our approach is based on probabilistic logic programming, which is especially useful for this purpose since it allows the representation of imprecise probabilities. All work in this area up to now has focused on the problem of entailment (verifying if a query formula follows from the available knowledge). This thesis identifies and addresses several other complementary problems that need to be solved when deriving the probabilities of events: (i) computing most probable worlds, (ii) answering abduction queries; and (iii) reasoning about promises. We address different variants of these problems, propose exact and heuristic algorithms to scalably solve them, present empirical evaluations of their performance, and discuss their applications in real-world settings.Abstract. In this thesis, we propose automated negotiation models for complex scenarios. More specifically, we focus on (i) negotiations where agents have limited computational resources, and (ii) negotiations where negotiation parties are formed by more than a single individual (i.e., negotiation teams). In the former case, we propose a bilateral model that obtains statistically equivalent results to models that explore the whole non-linear utility function while using less computational resources. In the latter case, we propose automated negotiation models for a negotiation team that negotiates with an opponent by means of the bilateral alternating protocol. We put a special emphasis on models that are able to guarantee unanimity with regards to team decisions in the negotiation.Abstract. This work proposes a novel methodology to improve the discovery of quantitative association rules in continuous datasets. This methodology comprises several evolutionary algorithms able to deal with real-valued variables without performing a static discretization process. Additionally, several quality measures are analysed to select the set of measures to be optimized with the aim of finding high-quality rules.Abstract. This thesis proposes a model that enhances service discovery in open Service-Oriented Multi-Agent Systems. In this model, agents have a bounded rationality, environment conditions do not remain constant, and not all the agents have a cooperative behavior. Our proposal integrates a network structure and search strategy as well as self-organization mechanisms and strategies for promoting cooperation in open and dynamic environments.