Exact Decoding on Latent Variable Conditional Models is NP-Hard.
http://arxiv.org/abs/1406.4682
@article{DBLP:journals/corr/Sun14a,
author = {Xu Sun},
title = {Exact Decoding on Latent Variable Conditional Models is NP-Hard},
journal = {CoRR},
volume = {abs/1406.4682},
year = {2014},
url = {http://arxiv.org/abs/1406.4682},
archivePrefix = {arXiv},
eprint = {1406.4682},
timestamp = {Mon, 15 Oct 2018 16:12:14 +0200},
biburl = {https://dblp.org/rec/journals/corr/Sun14a.bib},
bibsource = {dblp computer science bibliography, https://dblp.org}
}