@article{homotopyrelationsfordigitalimages,
  title = {Homotopy relations for digital images},
  author = {Laurence Boxer and P. Christopher Staecker},
  year = {2015},
  eprint = {1509.06576},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1509.06576v2},
}