@inproceedings{CTT100721904,
  author = {Tatsuya Imai and Kotaro Nakagawa and Aduri Pavan and Variyam Vinochandran and Osamu Watanabe},
  title = {An O(sqrt(n)+eps})-Space Algorithm for Directed Planar Reachability with Polynomial Running Time},
  booktitle = {情処研報 AL},
  year = 2013,
}

@inproceedings{CTT100717798,
  author = {Tatsuya Imai and Kotaro Nakagawa and A. Pavan and N.V. Vinodchandran and Osamu Watanabe},
  title = {An O(n^{{1/2}+epsilon}})-space and polynomial-time algorithm for directed planar reachability},
  booktitle = {Computational Complexity (CCC), 2013 IEEE Conference on},
  year = 2013,
}