R1, R2: Formal definition of VCD

We thank the reviewers for their valuable suggestions. Please find our answers ( A) for each reviewer ( R) below. A: We will add the following definition: VCDpX, Hq " max | X In particular, we will clarify that the teacher knows the learner's preference This is the protocol used in existing teaching models for both the batch settings (e.g., as in RTD / PBTD (line 221). We will further add a discussion on this in the updated version of the paper. R4: Discussion on the "presumably increased complexity of sequential learners" We will add a discussion in the updated version of the paper.