Vladimir Lifschitz, Alexander A. Razborov. Why are there so many loop formulas?. ACM Trans. Comput. Log., 7(2):261-268, 2006. [doi]
@article{LifschitzR06:0,
title = {Why are there so many loop formulas?},
author = {Vladimir Lifschitz and Alexander A. Razborov},
year = {2006},
doi = {10.1145/1131313.1131316},
url = {http://doi.acm.org/10.1145/1131313.1131316},
researchr = {https://researchr.org/publication/LifschitzR06%3A0},
cites = {0},
citedby = {0},
journal = {ACM Trans. Comput. Log.},
volume = {7},
number = {2},
pages = {261-268},
}