  Text detoxification is a conditional text generation task aiming to remove
offensive content from toxic text. It is highly useful for online forums and
social media, where offensive content is frequently encountered. Intuitively,
there are diverse ways to detoxify sentences while preserving their meanings,
and we can select from detoxified sentences before displaying text to users.
Conditional diffusion models are particularly suitable for this task given
their demonstrated higher generative diversity than existing conditional text
generation models based on language models. Nonetheless, text fluency declines
when they are trained with insufficient data, which is the case for this task.
In this work, we propose DiffuDetox, a mixed conditional and unconditional
diffusion model for text detoxification. The conditional model takes toxic text
as the condition and reduces its toxicity, yielding a diverse set of detoxified
sentences. The unconditional model is trained to recover the input text, which
allows the introduction of additional fluent text for training and thus ensures
text fluency. Extensive experimental results and in-depth analysis demonstrate
the effectiveness of our proposed DiffuDetox.
