Hierarchical Knowledge Organization In the previous papers, automatic knowledge organization for the procedural tasks was introduced which was based on the execution trace to solve the specific task and partial ordering between tasks. Partial ordering was applied to the natural language grammar and the skill difficulty was measured in the following manner: problem a is considered easier than b if b contains all the concepts that are in a. In the graphs this relation is shown by the edge from a to b. This method can be difficult to use when there are large amount of concepts. In order to eliminate this problem new fuzzy partial ordering graph is proposed.

Knowledge Assessment and Computer Based Test IRT (item response theory) and CAT (Computerized Adaptive Test) use user responses in order to update the information about student ability and item difficulty. However they have difficulties when there are fresh items since there is no student responses. "In contrast, our work measures the difficulty of online learning materials by studying the compositionality of domain knowledge and building the hierarchical knowledge structure within the corpus"

Educational Recommender Systems Educational recommender systems are mostly used in the formal learning scenarios like universities. In such environments experts design material and additionally there are pre-assessments or pre-questionnaires. In the case of online learning (informal learning situation) there is lack of structured data. The authors of this papers try to solve this issue by automatically ordering from the learning material that is retrieved from the Internet.