Before revision:  Our system leverages both supervised and unsupervised approaches to provide informative answers using DenSPI (Seo et al. , 2019) and BEST (Lee et al., 2016).
After revision:  Our system also leverages information retrieval (IR) approaches to provide informative answers using DenSPI (Seo et al. , 2019) and BEST (Lee et al., 2016).