Title
Improved 3LIN Hardness via Linear Label Cover.
Abstract
We prove that for every constant c and epsilon = (log n)^{-c}, there is no polynomial time algorithm that when given an instance of 3-LIN with n variables where an (1 - epsilon)-fraction of the clauses are satisfiable, finds an assignment that satisfies atleast (1/2 + epsilon)-fraction of clauses unless NP subseteq BPP. The previous best hardness using a polynomial time reduction achieves epsilon = (log log n)^{-c}, which is obtained by the Label Cover hardness of Moshkovitz and Raz [J. ACM, 57(5), 2010] followed by the reduction from Label Cover to 3-LIN of Hastad [J. ACM, 48(4):798 - 859, 2001].\r\nOur main idea is to prove a hardness result for Label Cover similar to Moshkovitz and Raz where each projection has a linear structure. This linear structure of Label Cover allows us to use Hadamard codes instead of long codes, making the reduction more efficient. For the hardness of Linear Label Cover, we follow the work of Dinur and Harsha [SIAM J. Comput., 42(6):2452 - 2486, 2013] that simplified the construction of Moshkovitz and Raz, and observe that running their reduction from a hardness of the problem LIN (of unbounded arity) instead of the more standard problem of solving quadratic equations ensures the linearity of the resultant Label Cover.
Year
DOI
Venue
2019
10.4230/LIPIcs.APPROX-RANDOM.2019.9
international workshop and international workshop on approximation, randomization, and combinatorial optimization. algorithms and techniques
DocType
Volume
Citations 
Conference
26
0
PageRank 
References 
Authors
0.34
0
4
Name
Order
Citations
PageRank
Prahladh Harsha137132.06
Subhash Khot22064112.51
Euiwoong Lee34715.45
Devanathan Thiruvenkatachari401.69