Section 1. Chapter 1. A comparative study of the functionalities and characteristics of a learner model in adaptive hypermedia educational systems ; Chapter 2. A comparative study of the modeling techniques and models of a learner model in adaptive hypermedia educational systems ; Chapter 3. Development of bayesian networks from use case diagrams for managing the learner model -- Section 2. Chapter 4. A learner model based on bayesian networks in adaptive educational hypermedia systems ; Chapter 5. The determination of learning styles in a learner model using the combination of Bayesian network and the overlay model ; Chapter 6. The combination of bayesian networks and stereotypes to initialize the learner model in adaptive educational hypermedia systems ; Chapter 7. A learner model based on multi-entity Bayesian networks in adaptive hypermedia educational systems.