All reports by Author Amey Bhangale:

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TR22-061
| 30th April 2022
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Amey Bhangale, Subhash Khot, Dor Minzer#### On Approximability of Satisfiable $k$-CSPs: I

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TR21-142
| 1st October 2021
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Amey Bhangale, Prahladh Harsha, Sourya Roy#### Mixing of 3-term progressions in Quasirandom Groups

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TR20-130
| 30th August 2020
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Amey Bhangale, Subhash Khot#### Optimal Inapproximability of Satisfiable k-LIN over Non-Abelian Groups

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TR20-075
| 6th May 2020
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Amey Bhangale, Prahladh Harsha, Orr Paradise, Avishay Tal#### Rigid Matrices From Rectangular PCPs

Revisions: 2

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TR19-148
| 1st November 2019
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Amey Bhangale, Subhash Khot#### Simultaneous Max-Cut is harder to approximate than Max-Cut

Revisions: 1

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TR19-048
| 2nd April 2019
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Per Austrin, Amey Bhangale, Aditya Potukuchi#### Simplified inpproximability of hypergraph coloring via t-agreeing families

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TR19-004
| 11th January 2019
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Amey Bhangale, Subhash Khot#### UG-hardness to NP-hardness by Losing Half

Revisions: 1

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TR18-073
| 21st April 2018
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Amey Bhangale#### NP-hardness of coloring $2$-colorable hypergraph with poly-logarithmically many colors

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TR17-030
| 15th February 2017
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Amey Bhangale, Subhash Khot, Devanathan Thiruvenkatachari#### An Improved Dictatorship Test with Perfect Completeness

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TR16-205
| 22nd December 2016
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Amey Bhangale, Irit Dinur, Inbal Livni Navon#### Cube vs. Cube Low Degree Test

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TR16-112
| 18th July 2016
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Mohammad T. Hajiaghayi, Amey Bhangale, Rajiv Gandhi, Rohit Khandekar, Guy Kortsarz#### Bicovering: Covering edges with two small subsets of vertices

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TR15-069
| 21st April 2015
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Amey Bhangale, Ramprasad Saptharishi, Girish Varma, Rakesh Venkat#### On Fortification of General Games

Revisions: 1

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TR14-098
| 30th July 2014
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Amey Bhangale, Swastik Kopparty, Sushant Sachdeva#### Simultaneous Approximation of Constraint Satisfaction Problems

Amey Bhangale, Subhash Khot, Dor Minzer

We consider the $P$-CSP problem for $3$-ary predicates $P$ on satisfiable instances. We show that under certain conditions on $P$ and a $(1,s)$ integrality gap instance of the $P$-CSP problem, it can be translated into a dictatorship vs. quasirandomness test with perfect completeness and soundness $s+\varepsilon$, for every constant $\varepsilon>0$. ... more >>>

Amey Bhangale, Prahladh Harsha, Sourya Roy

In this note, we show the mixing of three-term progressions $(x, xg, xg^2)$ in every finite quasirandom group, fully answering a question of Gowers. More precisely, we show that for any $D$-quasirandom group $G$ and any three sets $A_1, A_2, A_3 \subset G$, we have

\[ \left|\Pr_{x,y\sim G}\left[ x \in ...
more >>>

Amey Bhangale, Subhash Khot

A seminal result of H\r{a}stad [J. ACM, 48(4):798–859, 2001] shows that it is NP-hard to find an assignment that satisfies $\frac{1}{|G|}+\varepsilon$ fraction of the constraints of a given $k$-LIN instance over an abelian group, even if there is an assignment that satisfies $(1-\varepsilon)$ fraction of the constraints, for any constant ... more >>>

Amey Bhangale, Prahladh Harsha, Orr Paradise, Avishay Tal

We introduce a variant of PCPs, that we refer to as *rectangular* PCPs, wherein proofs are thought of as square matrices, and the random coins used by the verifier can be partitioned into two disjoint sets, one determining the *row* of each query and the other determining the *column*.

We ... more >>>

Amey Bhangale, Subhash Khot

A systematic study of simultaneous optimization of constraint satisfaction problems was initiated in [BKS15]. The simplest such problem is the simultaneous Max-Cut. [BKKST18] gave a $.878$-minimum approximation algorithm for simultaneous Max-Cut which is {\em almost optimal} assuming the Unique Games Conjecture (UGC). For a single instance Max-Cut, [GW95] gave an ... more >>>

Per Austrin, Amey Bhangale, Aditya Potukuchi

We reprove the results on the hardness of approximating hypergraph coloring using a different technique based on bounds on the size of extremal $t$-agreeing families of $[q]^n$. Specifically, using theorems of Frankl-Tokushige [FT99], Ahlswede-Khachatrian [AK98] and Frankl [F76] on the size of such families, we give simple and unified proofs ... more >>>

Amey Bhangale, Subhash Khot

The $2$-to-$2$ Games Theorem of [KMS-1, DKKMS-1, DKKMS-2, KMS-2] implies that it is NP-hard to distinguish between Unique Games instances with assignment satisfying at least $(\frac{1}{2}-\varepsilon)$ fraction of the constraints $vs.$ no assignment satisfying more than $\varepsilon$ fraction of the constraints, for every constant $\varepsilon>0$. We show that the reduction ... more >>>

Amey Bhangale

We give very short and simple proofs of the following statements: Given a $2$-colorable $4$-uniform hypergraph on $n$ vertices,

(1) It is NP-hard to color it with $\log^\delta n$ colors for some $\delta>0$.

(2) It is $quasi$-NP-hard to color it with $O\left({\log^{1-o(1)} n}\right)$ colors.

In terms of ... more >>>

Amey Bhangale, Subhash Khot, Devanathan Thiruvenkatachari

A Boolean function $f:\{0,1\}^n\rightarrow \{0,1\}$ is called a dictator if it depends on exactly one variable i.e $f(x_1, x_2, \ldots, x_n) = x_i$ for some $i\in [n]$. In this work, we study a $k$-query dictatorship test. Dictatorship tests are central in proving many hardness results for constraint satisfaction problems.

... more >>>Amey Bhangale, Irit Dinur, Inbal Livni Navon

We revisit the Raz-Safra plane-vs.-plane test and study the closely related cube vs. cube test. In this test the tester has access to a "cubes table" which assigns to every cube a low degree polynomial. The tester randomly selects two cubes (affine sub-spaces of dimension $3$) that intersect on a ... more >>>

Mohammad T. Hajiaghayi, Amey Bhangale, Rajiv Gandhi, Rohit Khandekar, Guy Kortsarz

We study the following basic problem called Bi-Covering. Given a graph $G(V,E)$, find two (not necessarily disjoint) sets $A\subseteq V$ and $B\subseteq V$ such that $A\cup B = V$ and that every edge $e$ belongs to either the graph induced by $A$ or to the graph induced by $B$. The ... more >>>

Amey Bhangale, Ramprasad Saptharishi, Girish Varma, Rakesh Venkat

A recent result of Moshkovitz~\cite{Moshkovitz14} presented an ingenious method to provide a completely elementary proof of the Parallel Repetition Theorem for certain projection games via a construction called fortification. However, the construction used in \cite{Moshkovitz14} to fortify arbitrary label cover instances using an arbitrary extractor is insufficient to prove parallel ... more >>>

Amey Bhangale, Swastik Kopparty, Sushant Sachdeva

Given $k$ collections of 2SAT clauses on the same set of variables $V$, can we find one assignment that satisfies a large fraction of clauses from each collection? We consider such simultaneous constraint satisfaction problems, and design the first nontrivial approximation algorithms in this context.

Our main result is that ... more >>>