I am working on classifying the Omniglot dataset and the different papers dealing with this topic describe the problem as one-shot learning (classification). I would like to nail down a precise description of what counts as one-shot learning. It's clear to me that in one-shot classification, a model tries to classify an input into one of $C$ classes by comparing it to exactly one example from each of the $C$ classes. What I want to understand is:
Is it necessary that the model has never seen the input and the target examples before, for the problem to be called one-shot?
Goodfellow et. al. describe one-shot learning as an extreme case transfer learning where only one labeled example of the transfer task is presented. So it means they are considering the training process as a kind of continuous transfer learning? What has the model learned earlier, that is being transferred?