Question: Why do the authors propose a generalized optimization-based meta-learning algorithm?
Evidence: As an essential part of a task-oriented dialogue system BIBREF0 , the task of natural language generation (NLG) is to produce a natural language utterance containing the desired information given a semantic representation consisting of dialogue act types with a set of slot-value pairs. Conventional methods using hand-crafted rules often generates monotonic utterances and it requires substantial amount of human engineering work. Recently, various neural approaches BIBREF1 , BIBREF2 , BIBREF3 have been proposed to generate accurate, natural and diverse utterances. However, these methods are typically developed for particular domains. Moreover, they are often data-intensive to train. The high annotation cost prevents developers to build their own NLG component from scratch. Therefore, it is extremely useful to train a NLG model that can be generalized to other NLG domains or tasks with a reasonable amount of annotated data. This is referred to low-resource NLG task in this paper.
Recently, some methods have been proposed for low-resource NLG tasks. Apart from the simple data augmentation trick BIBREF4 , specialized model architectures, including conditional variational auto-encoders (CVAEs, BIBREF3 , BIBREF5 , BIBREF6 ) and adversarial domain adaptation critics BIBREF5 , have been proposed to learn domain-invariant representations. Although promising results were reported, we found that datasets used by these methods are simple which tend to enumerate many slots and values in an utterance without much linguistic variations. As a consequence, over-fitting the slots and values in the low-resource target domain could even outperform those versions trained with rich source domain examples BIBREF6 . Fortunately, there is a new large-scale dialog dataset (MultiWoz, BIBREF7 ) that contains a great variety of domains and linguistic patterns that allows us to conduct extensive and meaningful experimental analysis for low-resource NLG tasks.
In this paper, instead of casting the problem as model-based approaches, we propose a generalized optimization-based meta-learning approach to directly enhance the optimization procedure for the low-resource NLG task. We start by arguing that a recently proposed model-agnostic meta-learning algorithm (MAML, BIBREF8 ) is a nice fit to the low-resource NLG task. Then, we proposed a generalized NLG algorithm called Meta-NLG based on MAML by viewing languages in different domains or dialog act types as separate Meta NLG tasks. Following the essence of MAML, the goal of Meta-NLG is to learn a better initialization of model parameters that facilitates fast adaptation to new low-resource NLG scenarios. As Meta-NLG is model-agnostic as long as the model can be optimized by gradient descent, we could apply it to any existing NLG models to optimize them in a way that adapt better and faster to new low-resource tasks.
The main contribution of this paper is two-fold:
In this paper, instead of casting the problem as model-based approaches, we propose a generalized optimization-based meta-learning approach to directly enhance the optimization procedure for the low-resource NLG task.
Answer: It is used to improve the optimization procedure for the low-resource natural language generation (NLG) task of natural language generation (NLG).