On Accurate Evaluation of GANs for Language Generation

Stanislau Semeniuta, Aliaksei Severyn, Sylvain Gelly

Abstract: Generative Adversarial Networks (GANs) are a promising approach to language generation. The latest works introducing novel GAN models for language generation use n-gram based metrics for evaluation and only report single scores of the best run. In this paper, we argue that this often misrepresents the true picture and does not tell the full story, as GAN models can be extremely sensitive to the random initialization and small deviations from the best hyperparameter choice. In particular, we demonstrate that the previously used BLEU score is not sensitive to semantic deterioration of generated texts and propose alternative metrics that better capture the quality and diversity of the generated samples. We also conduct a set of experiments comparing a number of GAN models for text with a conventional Language Model (LM) and find that none of the considered models performs convincingly better than the LM.

Keywords: GANs, Evaluation, Generative Models

TL;DR: We discuss how to evaluate GANs for language generation, propose a protocol and show that simple Language Models achieve results as good as GANs.