All reports by Author Euiwoong Lee:

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TR20-086
| 5th June 2020
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Andreas Feldmann, Karthik C. S., Euiwoong Lee, Pasin Manurangsi#### A Survey on Approximation in Parameterized Complexity: Hardness and Algorithms

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TR19-093
| 15th July 2019
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Prahladh Harsha, Subhash Khot, Euiwoong Lee, Devanathan Thiruvenkatachari#### Improved 3LIN Hardness via Linear Label Cover

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TR18-097
| 15th May 2018
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Vijay Bhattiprolu, Mrinalkanti Ghosh, Venkatesan Guruswami, Euiwoong Lee, Madhur Tulsiani#### Approximating Operator Norms via Generalized Krivine Rounding

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TR18-037
| 21st February 2018
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Vijay Bhattiprolu, Mrinalkanti Ghosh, Venkatesan Guruswami, Euiwoong Lee, Madhur Tulsiani#### Inapproximability of Matrix $p \rightarrow q$ Norms

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TR16-185
| 18th November 2016
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Vijay Bhattiprolu, Mrinalkanti Ghosh, Venkatesan Guruswami, Euiwoong Lee, Madhur Tulsiani#### Multiplicative Approximations for Polynomial Optimization Over the Unit Sphere

Revisions: 1

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TR15-155
| 22nd September 2015
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Venkatesan Guruswami, Euiwoong Lee#### Nearly Optimal NP-Hardness of Unique Coverage

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TR15-105
| 21st June 2015
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Venkatesan Guruswami, Euiwoong Lee#### Towards a Characterization of Approximation Resistance for Symmetric CSPs

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TR14-043
| 2nd April 2014
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Venkatesan Guruswami, Euiwoong Lee#### Strong Inapproximability Results on Balanced Rainbow-Colorable Hypergraphs

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TR14-006
| 16th January 2014
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Venkatesan Guruswami, Euiwoong Lee#### Inapproximability of Feedback Vertex Set for Bounded Length Cycles

Revisions: 1

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TR13-125
| 11th September 2013
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Venkatesan Guruswami, Euiwoong Lee#### Complexity of approximating CSP with Balance / Hard Constraints

Andreas Feldmann, Karthik C. S., Euiwoong Lee, Pasin Manurangsi

Parameterization and approximation are two popular ways of coping with NP-hard problems. More recently, the two have also been combined to derive many interesting results. We survey developments in the area both from the algorithmic and hardness perspectives, with emphasis on new techniques and potential future research directions.

more >>>Prahladh Harsha, Subhash Khot, Euiwoong Lee, Devanathan Thiruvenkatachari

We prove that for every constant $c$ and $\epsilon = (\log n)^{-c}$, there is no polynomial time algorithm that when given an instance of 3LIN with $n$ variables where an $(1 - \epsilon)$-fraction of the clauses are satisfiable, finds an assignment that satisfies at least $(\frac{1}{2} + \epsilon)$-fraction of clauses ... more >>>

Vijay Bhattiprolu, Mrinalkanti Ghosh, Venkatesan Guruswami, Euiwoong Lee, Madhur Tulsiani

We consider the $(\ell_p,\ell_r)$-Grothendieck problem, which seeks to maximize the bilinear form $y^T A x$ for an input matrix $A \in {\mathbb R}^{m \times n}$ over vectors $x,y$ with $\|x\|_p=\|y\|_r=1$. The problem is equivalent to computing the $p \to r^\ast$ operator norm of $A$, where $\ell_{r^*}$ is the dual norm ... more >>>

Vijay Bhattiprolu, Mrinalkanti Ghosh, Venkatesan Guruswami, Euiwoong Lee, Madhur Tulsiani

We study the problem of computing the $p\rightarrow q$ norm of a matrix $A \in R^{m \times n}$, defined as \[ \|A\|_{p\rightarrow q} ~:=~ \max_{x \,\in\, R^n \setminus \{0\}} \frac{\|Ax\|_q}{\|x\|_p} \] This problem generalizes the spectral norm of a matrix ($p=q=2$) and the Grothendieck problem ($p=\infty$, $q=1$), and has been ... more >>>

Vijay Bhattiprolu, Mrinalkanti Ghosh, Venkatesan Guruswami, Euiwoong Lee, Madhur Tulsiani

We consider the following basic problem: given an $n$-variate degree-$d$ homogeneous polynomial $f$ with real coefficients, compute a unit vector $x \in \mathbb{R}^n$ that maximizes $|f(x)|$. Besides its fundamental nature, this problem arises in many diverse contexts ranging from tensor and operator norms to graph expansion to quantum information ... more >>>

Venkatesan Guruswami, Euiwoong Lee

The {\em Unique Coverage} problem, given a universe $V$ of elements and a collection $E$ of subsets of $V$, asks to find $S \subseteq V$ to maximize the number of $e \in E$ that intersects $S$ in {\em exactly one} element. When each $e \in E$ has cardinality at most ... more >>>

Venkatesan Guruswami, Euiwoong Lee

A Boolean constraint satisfaction problem (CSP) is called approximation resistant if independently setting variables to $1$ with some probability $\alpha$ achieves the best possible approximation ratio for the fraction of constraints satisfied. We study approximation resistance of a natural subclass of CSPs that we call Symmetric Constraint Satisfaction Problems (SCSPs), ... more >>>

Venkatesan Guruswami, Euiwoong Lee

Consider a $K$-uniform hypergraph $H = (V,E)$. A coloring $c : V \rightarrow \{1, 2, \dots, k \}$ with $k$ colors is rainbow if every hyperedge $e$ contains at least one vertex from each color, and is called perfectly balanced when each color appears the same number of times. A ... more >>>

Venkatesan Guruswami, Euiwoong Lee

The Feedback Vertex Set problem (FVS), where the goal is to find a small subset of vertices that intersects every cycle in an input directed graph, is among the fundamental problems whose approximability is not well-understood. One can efficiently find an $\widetilde{O}(\log n)$ factor approximation, and while a constant-factor approximation ... more >>>

Venkatesan Guruswami, Euiwoong Lee

We study two natural extensions of Constraint Satisfaction Problems (CSPs). {\em Balance}-Max-CSP requires that in any feasible assignment each element in the domain is used an equal number of times. An instance of {\em Hard}-Max-CSP consists of {\em soft constraints} and {\em hard constraints}, and the goal is to maximize ... more >>>