Defense against Adversarial Attacks in NLP via Dirichlet Neighborhood Ensemble

Understand

Despite neural networks have achieved prominent performance on many natural language processing (NLP) tasks, they are vulnerable to adversarial examples.

• In this paper, we propose Dirichlet Neighborhood Ensemble (DNE), a randomized smoothing method for training a robust model to defense substitution-based attacks.
• During training, DNE forms virtual sentences by sampling embedding vectors for each word in an input sentence from a convex hull spanned by the word and its synonyms, and it augments them with the training data.
• In such a way, the model is robust to adversarial attacks while maintaining the performance on the original clean data.