Adam Woryna. The concept of duality for automata over a changing alphabet and generation of a free group by such automata. Theoretical Computer Science, 412(45):6420-6431, 2011. [doi]
@article{Woryna11,
title = {The concept of duality for automata over a changing alphabet and generation of a free group by such automata},
author = {Adam Woryna},
year = {2011},
doi = {10.1016/j.tcs.2011.08.017},
url = {http://dx.doi.org/10.1016/j.tcs.2011.08.017},
researchr = {https://researchr.org/publication/Woryna11},
cites = {0},
citedby = {0},
journal = {Theoretical Computer Science},
volume = {412},
number = {45},
pages = {6420-6431},
}