Designing and maintaining ontologies is a cumbersome and error-prone task. In most
of the cases, during the design phase, the ontology engineer cannot fully specify the
relationships between the classes of the application domain either because there are too
many of them or because he does not have a complete list of these relationships ready at
hand. In such cases, automated tools are not of much use either, since this task requires
comprehensive knowledge of the application domain, which means that interaction with
a domain expert is required. What one can use to solve this problems is
a semi-automated tool that learns the application domain from a domain expert. More
precisely, this method should be able to interactively acquire domain knowledge from an
expert in order to support the design or maintenance of the ontology.
An interactive knowledge acquisition algorithm developed in Formal Concept Analysis (FCA)
can be used to solve these problems. FCA  is a field of applied mathematics that is based on
a lattice-theoretic formalization of the notions of concept and conceptual hierarchy. It has
been successfully used in many areas of computer science including data analysis, data
mining and machine learning.

In this tutorial we are going to introduce FCA, and present FCA-based methods that support
ontology engineers in design and maintanence of ontologies. We are also going to
give a hands on demonstration of the tools that implement these methods.