  Many domain adaptation approaches rely on learning cross domain shared
representations to transfer the knowledge learned in one domain to other
domains. Traditional domain adaptation only considers adapting for one task. In
this paper, we explore multi-task representation learning under the domain
adaptation scenario. We propose a neural network framework that supports domain
adaptation for multiple tasks simultaneously, and learns shared representations
that better generalize for domain adaptation. We apply the proposed framework
to domain adaptation for sequence tagging problems considering two tasks:
Chinese word segmentation and named entity recognition. Experiments show that
multi-task domain adaptation works better than disjoint domain adaptation for
each task, and achieves the state-of-the-art results for both tasks in the
social media domain.
