This paper is concerned with the combinatorial structure of concept classes that can be learned from a small number of examples. We show that the recently introduced notion of recursive teaching dimension (RTD, reflecting the complexity of teaching a concept class) is a relevant parameter in this context. Comparing the RTD to self-directed learning, we establish new lower bounds on the query complexity for a variety of query learning models and thus
connect teaching to query learning
For many general cases, the RTD is upper-bounded by the VC-dimension, e.g., classes of VC-dimension 1, (nested differences of) intersection-closed classes, “standard” boolean function classes, and finite maximum classes. The RTD thus is the first model to
connect teaching to the VC-dimension
The combinatorial structure defined by the RTD has a remarkable resemblance to the structure exploited by sample compression schemes and hence
connects teaching to sample compression
. Sequences of teaching sets defining the RTD coincide with unlabeled compression schemes both (i) resulting from Rubinstein and Rubinstein’s corner-peeling and (ii) resulting from Kuzmin and Warmuth’s Tail Matching algorithm.