We present a simple generative framework for learning to predict previously unseen classes, based on estimating class-attribute-gated class-conditional distributions. We model each class-conditional distribution as an exponential family distribution and the parameters of the distribution of each seen/unseen class are defined as functions of the respective observed class attributes. These functions can be learned using only the seen class data and can be used to predict the parameters of the class-conditional distribution of each unseen class. Unlike most existing methods for zero-shot learning that represent classes as fixed embeddings in some vector space, our generative model naturally represents each class as a probability distribution. It is simple to implement and also allows leveraging additional unlabeled data from unseen classes to improve the estimates of their class-conditional distributions using transductive/semi-supervised learning. Moreover, it extends seamlessly to few-shot learning by easily updating these distributions when provided with a small number of additional labelled examples from unseen classes. Through a comprehensive set of experiments on several benchmark data sets, we demonstrate the efficacy of our framework.

提出了一个简单的生成模型框架，用于学习预测以前未见过的类，该模型通过估计门限类条件属性分布来实现，与大多数现有的零样本学习方法不同，我们的生成模型自然地将每个类表示为概率分布，可以无缝扩展到少样本学习，并通过在训练过程中使用来自未见过的类的未标记数据提高其条件分布的估计效率。

零样本学习的简单指数族框架