Learning Similarities for Informally Defined Objects

Learning is considered as an essential aspect of intelligence. It takes usually place in some context where one learns from an environment. There are various forms of learning: How to learn and what to learn. Here we are concerned with learning of informal concepts. Informal concepts occur in many forms: Heuristics, personal judgements, utterances about taste etc. Such concepts provide to major difficulties: 1) Informal concepts do not have a precise definition and often not a definition at all. 2) Informal concepts are subjective and their interpretation depends on persons or groups of persons. 3) Not the concepts themselves play the major role but rather the way one uses them. The use is manifold but mainly connected with decisions for or against a behavior or an action. 4) The concepts and the use of the concepts have to be learned. 5) There is no sharp measurement of what the meaning of ‘successful learning’ is: The learning success is again something imprecise. As a consequence, the approximation character of the learning process is central.