A new theory of subjective probability is presented. According to this theory, different descriptions of the same event can give rise to different judgments. Experimental evidence supporting this theory is summarized, demonstrating that the theory provides a unified treatment of a wide range of empirical findings. (SLD)

This article gives a comprehensive description of a theory for efficient assessment of knowledge. The essential concept is that the knowledge state of a subject, with regard to a specified field of information, can be represented by a particular subset of problems that the subject is capable of solving. (SLD)