It is shown that the traveling salesman problem, where cities are bit
strings with Hamming distances, is NP-complete.
BibLATEX:
@article{EKP1985J,
author = {Jarmo Ernvall and Jyrki Katajainen and Martti Penttonen},
title = {{NP}-completeness of the {H}amming salesman problem},
journaltitle = {BIT},
volume = {25},
number = {1},
year = {1985},
pages = {289--292},
}