Before revision:  In this work, we propose a  Fast Gradient Projection Method (FGPM) to generate text adversarial examples based on synonym substitution, where each substitution is scored by the product of gradient magnitude and the projected distance between the original word and the candidate word in the gradient direction. Empirical evaluations demonstrate that FGPM achieves similar attack performance and transferability when compared with competitive attack baselines, at the same time it is about 20 times faster than the current fastest text attack method.
After revision:  In this work, we propose a Fast Gradient Projection Method (FGPM) to generate text adversarial examples based on synonym substitution, which is about 20 times faster than the current fastest text attack method.