Johan Håstad
Every 2-CSP allows nontrivial approximation
STOC, 2005.
@inproceedings{STOC-2005-Hastad, author = "Johan Håstad", booktitle = "{Proceedings of the 37th Annual ACM Symposium on Theory of Computing}", doi = "10.1145/1060590.1060700", isbn = "1-58113-960-8", pages = "740--746", publisher = "{ACM}", title = "{Every 2-CSP allows nontrivial approximation}", year = 2005, }