Improving the generalization of deep networks is an important open challenge, particularly in domains without plentiful data. The mixup algorithm improves generalization by linearly interpolating a pair of examples and their corresponding labels. These interpolated examples augment the original training set. Mixup has shown promising results in various classification tasks, but systematic analysis of mixup in regression remains underexplored. Using mixup directly on regression labels can result in arbitrarily incorrect labels.

This is the distribution over datasets one obtains by first sampling a task t from Pt, and then sampling a dataset S from Pmz|t. Here p(S) corresponds to the marginal distribution over datasets S. Note that the last line above holds because E P f(,S) does not depend on t. Thus, in this section, we present a specialization of the bound for Gaussian distributions. Let P have mean µ and covariance; thus P = N(µ,) and analogously P,0 = N(µ0, 0). We can then apply the analytical form for the KL-divergence between two multivariate Gaussian distributions to the bound presented in Theorem 3. The result is the following bound holding under the same assumptions as Theorem 3: L(P,Pt) 1 l We implement the above bound in code instead of the non-specialized form of the KL divergence to speed up computations and simplify gradient computations. A.3.2 Few-Shot Learning Bound with Validation Data In this section, we will assume that, in addition to the training data S Pmz|t, we have access to validation data Sva Pnz|t at meta-training time. We will show that a meta-learning generalization bound can still be obtained in this case.

We are motivated by the problem of providing strong generalization guarantees in the context of meta-learning. Existing generalization bounds are either challenging to evaluate or provide vacuous guarantees in even relatively simple settings. We derive a probably approximately correct (PAC) bound for gradient-based metalearning using two different generalization frameworks in order to deal with the qualitatively different challenges of generalization at the "base" and "meta" levels. We employ bounds for uniformly stable algorithms at the base level and bounds from the PAC-Bayes framework at the meta level. The result of this approach is a novel PAC bound that is tighter when the base learner adapts quickly, which is precisely the goal of meta-learning. We show that our bound provides a tighter guarantee than other bounds on a toy non-convex problem on the unit sphere and a text-based classification example. We also present a practical regularization scheme motivated by the bound in settings where the bound is loose and demonstrate improved performance over baseline techniques.