Tying weights in NLM: Reusing embeddings in word-level neural language models is a technique which was used earlier (Bengio et al., 2001;Mnih and Hinton, 2007) and studied in more details recently (Inan et al., 2017;Press and Wolf, 2017).
not much work has been done on reusing parameters in subword-aware or subwordlevel language models.