J
Johan Håstad
Researcher at Royal Institute of Technology
Publications - 171
Citations - 16664
Johan Håstad is an academic researcher from Royal Institute of Technology. The author has contributed to research in topics: Approximation algorithm & Mathematical proof. The author has an hindex of 50, co-authored 169 publications receiving 15806 citations. Previous affiliations of Johan Håstad include Massachusetts Institute of Technology.
Papers
More filters
Book ChapterDOI
On the efficient approximability of constraint satisfaction problems
TL;DR: Some results about the efficient approximability of constraint satisfaction problems are discussed and an efficient algorithm can perform significantly better than the algorithm that picks a solution uniformly at random.
Journal ArticleDOI
On Lower Bounds for Selecting the Median
TL;DR: A reformulation of the 2n+o(n) lower bound of Bent and John is presented for the number of comparisons needed for selecting the median of n elements to show that any pair-forming median finding algorithm must perform, in the worst case, at least 2.01 n + o(n).
Proceedings ArticleDOI
Top-down lower bounds for depth 3 circuits
TL;DR: This is the first simple proof of a strong lower bound by a top-down argument for non-monotone circuits and proves that depth 3 AND-OR-NOT circuits that compute PARITY resp.
Journal ArticleDOI
A well-characterized approximation problem
TL;DR: It is proved that in the case in which the polynomials do not contain any squares as monomials, it is always possible to approximate this problem within a factor of p2/(p-1) in polynomial time for fixed p, and it is NP-hard to approximate the solution of quadratic equations over the rational numbers, or over the reals within nδ.
Proceedings Article
A new way to use semidefinite programming with applications to linear equations mod p
TL;DR: A new method of constructing approximation algorithms for combinatorial optimization problems using semidefinite programming that consists of expressing each combinatorsial object in the original problem as a constellation of vectors in the semideFinite program is introduced.