The Hierarchy of Saturating Matching Numbers
Hans U. Simon, Jan Arne Telle
TL;DR
This work investigates three machine-teaching-inspired matching problems through the lens of combinatorial parameters: the saturating matching number $SMN$, the antichain matching number $AMN$, and the greedy variants $GMN$, including their primed versions. It establishes a hierarchy of inequalities among these parameters, studies their monotonicity and additivity properties, and analyzes their behavior on the powerset class $P_n$ to derive tight asymptotic bounds. The central contributions include the extremal results for the $(k,n)$-family via $C_{k,n}$, a bound of $AMN'(C)$ by $GMN'(C)$, and extensive structural analysis (monotonicity, additivity, and sub-additivity) that clarifies how these costs interact under domain and class extensions and free combinations. The paper also highlights the tightness of the hierarchy with concrete separations and ends with an open question on the sub-additivity of $GMN$, signaling directions for future work. Overall, the results connect teaching-map cost measures to classical learning theory parameters (like $VCD$ and RTD) and provide a comprehensive map of how these combinatorial quantities relate and differ in representational settings relevant to teaching and learning.
Abstract
In this paper, we study three matching problems all of which came up quite recently in the field of machine teaching. The cost of a matching is defined in such a way that, for some formal model of teaching, it equals (or bounds) the number of labeled examples needed to solve a given teaching task. We show how the cost parameters associated with these problems depend on each other and how they are related to other well known combinatorial parameters (like, for instance, the VC-dimension).
