@article{Dinur2001TheIO,
title={The Importance of Being Biased},
author={Irit Dinur and Shmuel Safra},
journal={Electronic Colloquium on Computational Complexity (ECCC)},
year={2001}
}

(MATH) We show that the Minimum Vertex Cover problem is NP-hard to approximate to within any factor smaller than $10\sqrt{5}-21 \approx 1.36067$, improving on the previously known hardness result for a $\frac{7}{6}$ factor.