The complexity of learning with queries

We survey recent research concerning the qualitative complexity of Angluin's (1993) model of learning with queries. In this model, there is a learner that tries to identify a target concept by means of queries to a teacher. Thus, the process can be naturally formulated as an oracle computation. Among the results we review there are: characterizations of the power of different learning protocols by complexity classes of oracle machines; relations between the complexity of learning and the complexity of computing advice functions for nonuniform classes; and combinatorial characterizations of the concept classes that are learnable in specific protocols.<
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