The $$k$$ k -separator problem: polyhedra, complexity and approximation results

Approximation Algorithms for NP-Hard Problems

Dorit S. Hochba · ACM SIGACT News · 1997 · 3.1K citations · Full text

Computing, Computer Science, Mathematics +13

Clique is hard to approximate within n1−ε

Johan Håstad · Acta Mathematica · 1999 · 1.4K citations · Full text

Computing, Computer Science, Algorithms +3

Easy problems for tree-decomposable graphs

Stefan Arnborg, Jens Lagergren, Detlef Seese · Journal of Algorithms · 1991 · 874 citations

Natural Sciences, Computer Science, Mathematics +9

Vertex cover might be hard to approximate to within<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mn>2</mml:mn><mml:mo>−</mml:mo><mml:mi>ε</mml:mi></mml:math>

Subhash Khot, Oded Regev · Journal of Computer and System Sciences · 2007 · 761 citations

Natural Sciences, Mathematics, Geometry +5

On the hardness of approximating vertex cover

Irit Dinur, Samuel Safra · Annals of Mathematics · 2005 · 635 citations · Full text

Computing, Computer Science, Mathematics +15