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All reports by Author Vikraman Arvind:

TR17-074 | 29th April 2017
Vikraman Arvind, Rajit Datta, Partha Mukhopadhyay, Raja S

Efficient Identity Testing and Polynomial Factorization over Non-associative Free Rings

Revisions: 1

In this paper we study arithmetic computations over non-associative, and non-commutative free polynomials ring $\mathbb{F}\{x_1,x_2,\ldots,x_n\}$. Prior to this work, the non-associative arithmetic model of computation was considered by Hrubes, Wigderson, and Yehudayoff [HWY10]. They were interested in completeness and explicit lower bound results.

We focus on two main problems ... more >>>

TR16-193 | 22nd November 2016
Vikraman Arvind, Pushkar Joglekar, Partha Mukhopadhyay, Raja S

Identity Testing for +-Regular Noncommutative Arithmetic Circuits

An efficient randomized polynomial identity test for noncommutative
polynomials given by noncommutative arithmetic circuits remains an
open problem. The main bottleneck to applying known techniques is that
a noncommutative circuit of size $s$ can compute a polynomial of
degree exponential in $s$ with a double-exponential number of nonzero
monomials. ... more >>>

TR16-157 | 13th October 2016
Vikraman Arvind, Johannes Köbler, Sebastian Kuhnert, Jacobo Toran

Parameterized Complexity of Small Weight Automorphisms

We consider the PermCode problem to decide, given a representation of a permutation group G and a parameter k, whether there is a non-trivial element of G with support at most k. This problem generalizes several problems in the literature. We introduce a new method that allows to reduce the ... more >>>

TR16-089 | 2nd June 2016
Vikraman Arvind, Partha Mukhopadhyay, Raja S

Randomized Polynomial Time Identity Testing for Noncommutative Circuits

Revisions: 2

In this paper we show that polynomial identity testing for
noncommutative circuits of size $s$, computing a polynomial in
$\mathbb{F}\langle z_1,z_2,\cdots,z_n \rangle$, can be done by a randomized algorithm
with running time polynomial in $s$ and $n$. This answers a question
that has been open for over ten years.

The ... more >>>

TR15-176 | 6th November 2015
Vikraman Arvind, Raja S

Some Lower Bound Results for Set-Multilinear Arithmetic Computations

Revisions: 1

In this paper, we study the structure of set-multilinear arithmetic
circuits and set-multilinear branching programs with the aim of
showing lower bound results. We define some natural restrictions of
these models for which we are able to show lower bound results. Some
of our results extend existing lower bounds, while ... more >>>

TR15-124 | 3rd August 2015
Vikraman Arvind, Pushkar Joglekar, Raja S

Noncommutative Valiant's Classes: Structure and Complete Problems

Revisions: 1

In this paper we explore the noncommutative analogues, $\mathrm{VP}_{nc}$ and
$\mathrm{VNP}_{nc}$, of Valiant's algebraic complexity classes and show some
striking connections to classical formal language theory. Our main
results are the following:

(1) We show that Dyck polynomials (defined from the Dyck languages of formal language theory) are complete for ... more >>>

TR15-032 | 21st February 2015
Vikraman Arvind, Johannes Köbler, Gaurav Rattan, Oleg Verbitsky

Graph Isomorphism, Color Refinement, and Compactness

Revisions: 2

Color refinement is a classical technique used to show that two given graphs $G$ and $H$
are non-isomorphic; it is very efficient, although it does not succeed on all graphs. We call a graph $G$ amenable to color refinement if the color-refinement procedure succeeds in distinguishing $G$ from any non-isomorphic ... more >>>

TR15-004 | 4th January 2015
Vikraman Arvind, Pushkar Joglekar, Gaurav Rattan

On the Complexity of Noncommutative Polynomial Factorization

In this paper we study the complexity of factorization of polynomials in the free noncommutative ring $\mathbb{F}\langle x_1,x_2,\ldots,x_n\rangle$ of polynomials over the field $\mathbb{F}$ and noncommuting variables $x_1,x_2,\ldots,x_n$. Our main results are the following.

Although $\mathbb{F}\langle x_1,\dots,x_n \rangle$ is not a unique factorization ring, we note that variable-disjoint factorization in ... more >>>

TR14-111 | 15th August 2014
Vikraman Arvind, Gaurav Rattan

Faster FPT Algorithm for Graph Isomorphism Parameterized by Eigenvalue Multiplicity

We give a $O^*(k^{O(k)})$ time isomorphism testing algorithm for graphs of eigenvalue multiplicity bounded by $k$ which improves on the previous
best running time bound of $O^*(2^{O(k^2/\log

more >>>

TR14-096 | 29th July 2014
Vikraman Arvind, Sebastian Kuhnert, Johannes Köbler, Jacobo Toran

Solving Linear Equations Parameterized by Hamming Weight

Given a system of linear equations $Ax=b$ over the binary field $\mathbb{F}_2$ and an integer $t\ge 1$, we study the following three algorithmic problems:
1. Does $Ax=b$ have a solution of weight at most $t$?
2. Does $Ax=b$ have a solution of weight exactly $t$?
3. Does $Ax=b$ have a ... more >>>

TR14-070 | 14th May 2014
Vikraman Arvind, Gaurav Rattan

The Complexity of Geometric Graph Isomorphism

We study the complexity of Geometric Graph Isomorphism, in
$l_2$ and other $l_p$ metrics: given two sets of $n$ points $A,
B\subset \mathbb{Q}^k$ in
$k$-dimensional euclidean space the problem is to
decide if there is a bijection $\pi:A \rightarrow B$ such that for
... more >>>

TR14-028 | 27th February 2014
Vikraman Arvind, S Raja

The Complexity of Two Register and Skew Arithmetic Computation

We study two register arithmetic computation and skew arithmetic circuits. Our main results are the following:

(1) For commutative computations, we show that an exponential circuit size lower bound
for a model of 2-register straight-line programs (SLPs) which is a universal model
of computation (unlike width-2 algebraic branching programs that ... more >>>

TR12-078 | 14th June 2012
Vikraman Arvind, Sebastian Kuhnert, Johannes Köbler, Yadu Vasudev

Approximate Graph Isomorphism

We study optimization versions of Graph Isomorphism. Given two graphs $G_1,G_2$, we are interested in finding a bijection $\pi$ from $V(G_1)$ to $V(G_2)$ that maximizes the number of matches (edges mapped to edges or non-edges mapped to non-edges). We give an $n^{O(\log n)}$ time approximation scheme that for any constant ... more >>>

TR11-140 | 31st October 2011
Vikraman Arvind, Partha Mukhopadhyay, Prajakta Nimbhorkar, Yadu Vasudev

Expanding Generator Sets for Solvable Permutation Groups

Revisions: 1

Let $G=\langle S\rangle$ be a solvable permutation group given as input by generating set $S$. I.e.\ $G$ is a solvable subgroup of the symmetric group $S_n$. We give a deterministic polynomial-time algorithm that computes an expanding generator set for $G$. More precisely, given a constant $\lambda <1$ we can compute ... more >>>

TR11-137 | 14th October 2011
Vikraman Arvind, Yadu Vasudev

Isomorphism Testing of Boolean Functions Computable by Constant Depth Circuits

Given two $n$-variable boolean functions $f$ and $g$, we study the problem of computing an $\varepsilon$-approximate isomorphism between them. I.e.\ a permutation $\pi$ of the $n$ variables such that $f(x_1,x_2,\ldots,x_n)$ and $g(x_{\pi(1)},x_{\pi(2)},\ldots,x_{\pi(n)})$ differ on at most an $\varepsilon$ fraction of all boolean inputs $\{0,1\}^n$. We give a randomized $2^{O(\sqrt{n}\log(n)^{O(1)})}$ algorithm ... more >>>

TR11-081 | 15th May 2011
Vikraman Arvind, Partha Mukhopadhyay, Prajakta Nimbhorkar

Erdos-Renyi Sequences and Deterministic construction of Expanding Cayley Graphs

Given a finite group $G$ by its multiplication table as input, we give a deterministic polynomial-time construction of a directed Cayley graph on $G$ with $O(\log |G|)$ generators, which has a rapid mixing property and a constant spectral expansion.\\

We prove a similar result in the undirected case, and ... more >>>

TR10-069 | 17th April 2010
Eric Allender, Vikraman Arvind, Fengming Wang

Uniform Derandomization from Pathetic Lower Bounds

Revisions: 1 , Comments: 1

A recurring theme in the literature on derandomization is that probabilistic
algorithms can be simulated quickly by deterministic algorithms, if one can obtain *impressive* (i.e., superpolynomial, or even nearly-exponential) circuit size lower bounds for certain problems. In contrast to what is
needed for derandomization, existing lower bounds seem rather pathetic ... more >>>

TR09-122 | 23rd November 2009
Vikraman Arvind, Srikanth Srinivasan

Circuit Lower Bounds, Help Functions, and the Remote Point Problem

We investigate the power of Algebraic Branching Programs (ABPs) augmented with help polynomials, and constant-depth Boolean circuits augmented with help functions. We relate the problem of proving explicit lower bounds in both these models to the Remote Point Problem (introduced by Alon, Panigrahy, and Yekhanin (RANDOM '09)). More precisely, proving ... more >>>

TR09-105 | 27th October 2009
Vikraman Arvind, Srikanth Srinivasan

The Remote Point Problem, Small Bias Spaces, and Expanding Generator Sets

Using $\epsilon$-bias spaces over F_2 , we show that the Remote Point Problem (RPP), introduced by Alon et al [APY09], has an $NC^2$ algorithm (achieving the same parameters as [APY09]). We study a generalization of the Remote Point Problem to groups: we replace F_n by G^n for an arbitrary fixed ... more >>>

TR09-103 | 26th October 2009
Vikraman Arvind, Srikanth Srinivasan

On the Hardness of the Noncommutative Determinant

In this paper we study the computational complexity of computing the noncommutative determinant. We first consider the arithmetic circuit complexity of computing the noncommutative determinant polynomial. Then, more generally, we also examine the complexity of computing the determinant (as a function) over noncommutative domains. Our hardness results are summarized below:

... more >>>

TR09-093 | 8th October 2009
Vikraman Arvind, Bireswar Das, Johannes Köbler, Seinosuke Toda

Colored Hypergraph Isomorphism is Fixed Parameter Tractable

Revisions: 1

We describe a fixed parameter tractable (fpt) algorithm for Colored Hypergraph Isomorphism} which has running time $b!2^{O(b)}N^{O(1)}$, where the parameter $b$ is the maximum size of the color classes of the given hypergraphs and $N$ is the input size. We also describe fpt algorithms for certain permutation group problems that ... more >>>

TR09-073 | 6th September 2009
Vikraman Arvind, Pushkar Joglekar, Srikanth Srinivasan

On Lower Bounds for Constant Width Arithmetic Circuits

The motivation for this paper is to study the complexity of constant-width arithmetic circuits. Our main results are the following.
1. For every k > 1, we provide an explicit polynomial that can be computed by a linear-sized monotone circuit of width 2k but has no subexponential-sized monotone circuit ... more >>>

TR09-026 | 17th February 2009
Vikraman Arvind, Pushkar Joglekar

Arithmetic Circuit Size, Identity Testing, and Finite Automata

Let $\F\{x_1,x_2,\cdots,x_n\}$ be the noncommutative polynomial
ring over a field $\F$, where the $x_i$'s are free noncommuting
formal variables. Given a finite automaton $\A$ with the $x_i$'s as
alphabet, we can define polynomials $\f( mod A)$ and $\f(div A)$
obtained by natural operations that we ... more >>>

TR08-086 | 9th July 2008
Vikraman Arvind, Partha Mukhopadhyay

Quantum Query Complexity of Multilinear Identity Testing

Motivated by the quantum algorithm in \cite{MN05} for testing
commutativity of black-box groups, we study the following problem:
Given a black-box finite ring $R=\angle{r_1,\cdots,r_k}$ where
$\{r_1,r_2,\cdots,r_k\}$ is an additive generating set for $R$ and a
multilinear polynomial $f(x_1,\cdots,x_m)$ over $R$ also accessed as
a ... more >>>

TR08-052 | 29th April 2008
Vikraman Arvind, T.C. Vijayaraghavan

The Orbit problem is in the GapL Hierarchy

Revisions: 1

The \emph{Orbit problem} is defined as follows: Given a matrix $A\in
\Q ^{n\times n}$ and vectors $\x,\y\in \Q ^n$, does there exist a
non-negative integer $i$ such that $A^i\x=\y$. This problem was
shown to be in deterministic polynomial time by Kannan and Lipton in
\cite{KL1986}. In this paper we place ... more >>>

TR08-049 | 10th April 2008
Vikraman Arvind, Partha Mukhopadhyay

Derandomizing the Isolation Lemma and Lower Bounds for Noncommutative Circuit Size

Revisions: 3

We give a randomized polynomial-time identity test for
noncommutative circuits of polynomial degree based on the isolation
lemma. Using this result, we show that derandomizing the isolation
lemma implies noncommutative circuit size lower bounds. More
precisely, we consider two restricted versions of the isolation
lemma and show that derandomizing each ... more >>>

TR08-025 | 3rd January 2008
Vikraman Arvind, Partha Mukhopadhyay, Srikanth Srinivasan

New results on Noncommutative and Commutative Polynomial Identity Testing

Revisions: 2

Using ideas from automata theory we design a new efficient
(deterministic) identity test for the \emph{noncommutative}
polynomial identity testing problem (first introduced and studied by
Raz-Shpilka in 2005 and Bogdanov-Wee in 2005). More precisely,
given as input a noncommutative
circuit $C(x_1,\cdots,x_n)$ computing a ... more >>>

TR07-095 | 13th July 2007
Vikraman Arvind, Partha Mukhopadhyay

The Ideal Membership Problem and Polynomial Identity Testing

Revisions: 2

Given a monomial ideal $I=\angle{m_1,m_2,\cdots,m_k}$ where $m_i$
are monomials and a polynomial $f$ as an arithmetic circuit the
\emph{Ideal Membership Problem } is to test if $f\in I$. We study
this problem and show the following results.
\item[(a)] If the ideal $I=\angle{m_1,m_2,\cdots,m_k}$ for a
more >>>

TR04-121 | 7th December 2004
Vikraman Arvind, Piyush Kurur, T.C. Vijayaraghavan

Bounded Color Multiplicity Graph Isomorphism is in the #L Hierarchy.

In this paper we study the complexity of Bounded Color
Multiplicity Graph Isomorphism (BCGI): the input is a pair of
vertex-colored graphs such that the number of vertices of a given
color in an input graph is bounded by $b$. We show that BCGI is in the
#L hierarchy ... more >>>

TR04-008 | 27th November 2003
Vikraman Arvind, Jacobo Toran

Solvable Group Isomorphism is (almost) in NP\cap coNP

The Group Isomorphism problem consists in deciding whether two input
groups $G_1$ and $G_2$ given by their multiplication tables are
isomorphic. We first give a 2-round Arthur-Merlin protocol for the
Group Non-Isomorphism problem such that on input groups $(G_1,G_2)$
of size $n$, Arthur uses ... more >>>

TR03-064 | 23rd June 2003
Vikraman Arvind, Piyush Kurur

Upper Bounds on the Complexity of some Galois Theory Problems

Given a polynomial f(X) with rational coefficients as input
we study the problem of (a) finding the order of the Galois group of
f(X), and (b) determining the Galois group of f(X) by finding a small
generator set. Assuming the generalized Riemann hypothesis, we prove
the following complexity bounds:

1. ... more >>>

TR02-037 | 21st May 2002
Vikraman Arvind, Piyush Kurur

Graph Isomorphism is in SPP

We show that Graph Isomorphism is in the complexity class
SPP, and hence it is in $\ParityP$ (in fact, it is in $\ModkP$ for
each $k\geq 2$). We derive this result as a corollary of a more
general result: we show that a {\em generic problem} $\FINDGROUP$ has
an $\FP^{\SPP}$ ... more >>>

TR02-031 | 30th April 2002
Vikraman Arvind, Venkatesh Raman

Approximate Counting small subgraphs of bounded treewidth and related problems

Revisions: 1

We give a randomized approximation algorithm taking
$O(k^{O(k)}n^{b+O(1)})$ time to count the number of copies of a
$k$-vertex graph with treewidth at most $b$ in an $n$ vertex graph
$G$ with approximation ratio $1/k^{O(k)}$ and error probability
inverse exponential in $n$. This algorithm is based on ... more >>>

TR99-033 | 19th August 1999
Vikraman Arvind, J. Köbler

Graph Isomorphism is Low for ZPP$^{\mbox{\rm NP}}$ and other Lowness results.

We show the following new lowness results for the probabilistic
class ZPP$^{\mbox{\rm NP}}$.

1. The class AM$\cap$coAM is low for ZPP$^{\mbox{\rm NP}}$.
As a consequence it follows that Graph Isomorphism and several
group-theoretic problems known to be in AM$\cap$coAM are low for
ZPP$^{\mbox{\rm ... more >>>

TR99-008 | 19th March 1999
Eric Allender, Vikraman Arvind, Meena Mahajan

Arithmetic Complexity, Kleene Closure, and Formal Power Series

Revisions: 1 , Comments: 1

The aim of this paper is to use formal power series techniques to
study the structure of small arithmetic complexity classes such as
GapNC^1 and GapL. More precisely, we apply the Kleene closure of
languages and the formal power series operations of inversion and
root ... more >>>

TR98-078 | 1st December 1998
Vikraman Arvind, K.V. Subrahmanyam, Vinodchandran Variyam

The Query Complexity of Program Checking by Constant-Depth Circuits

In this paper we study program checking (in the
sense of Blum and Kannan) using constant-depth circuits as
checkers. Our focus is on the number of queries made by the
checker to the program being checked and we term this as the
query complexity of the checker for the given ... more >>>

TR98-027 | 15th April 1998
Vikraman Arvind, Jacobo Toran

Sparse sets, approximable sets, and parallel queries to NP

We relate the existence of disjunctive hard sets for NP to
other well studied hypotheses in complexity theory showing
that if an NP-complete set or a coNP-complete set is
polynomial-time disjunctively reducible
to a sparse set then FP$^{\rm NP}_{||}$ = FP$^{\rm NP[log]}$. Using
a similar argument we obtain also that ... more >>>

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