Eric Allender, Klaus Reinhardt

We show that the perfect matching problem is in the

complexity class SPL (in the nonuniform setting).

This provides a better upper bound on the complexity of the

matching problem, as well as providing motivation for studying

the complexity class SPL.

Using similar ...
more >>>

Andris Ambainis, David Mix Barrington, Huong LeThanh

Continuing the study of the relationship between $TC^0$,

$AC^0$ and arithmetic circuits, started by Agrawal et al.

(IEEE Conference on Computational Complexity'97),

we answer a few questions left open in this

paper. Our main result is that the classes Diff$AC^0$ and

Gap$AC^0$ ...
more >>>

Eric Allender, Shiyu Zhou

We show that the complexity class LogFew is contained

in NL $\cap$ SPL. Previously, this was known only to

hold in the nonuniform setting.

Eric Allender, Andris Ambainis, David Mix Barrington, Samir Datta, Huong LeThanh

Constant-depth arithmetic circuits have been defined and studied

in [AAD97,ABL98]; these circuits yield the function classes #AC^0

and GapAC^0. These function classes in turn provide new

characterizations of the computational power of threshold circuits,

and provide a link between the circuit classes AC^0 ...
more >>>

Eric Allender, Michal Koucky, Detlef Ronneburger, Sambuddha Roy, V Vinay

We extend the lower bound techniques of [Fortnow], to the

unbounded-error probabilistic model. A key step in the argument

is a generalization of Nepomnjascii's theorem from the Boolean

setting to the arithmetic setting. This generalization is made

possible, due to the recent discovery of logspace-uniform TC^0

more >>>

Ran Raz

We prove a lower bound of $\Omega(m^2 \log m)$ for the size of

any arithmetic circuit for the product of two matrices,

over the real or complex numbers, as long as the circuit doesn't

use products with field elements of absolute value larger than 1

(where $m \times m$ is ...
more >>>

Vince Grolmusz

Elementary symmetric polynomials $S_n^k$ are used as a

benchmark for the bounded-depth arithmetic circuit model of computation.

In this work we prove that $S_n^k$ modulo composite numbers $m=p_1p_2$

can be computed with much fewer multiplications than over any field, if

the coefficients of monomials $x_{i_1}x_{i_2}\cdots x_{i_k}$ ...
more >>>

Matthias Galota, Heribert Vollmer

We show that the class of integer-valued functions computable by

polynomial-space Turing machines is exactly the class of functions f

for which there is a nondeterministic polynomial-time Turing

machine with a certain order on its paths that on input x outputs a 3x3

matrix with entries from {-1,0,1} on each ...
more >>>

Eric Allender, Peter Bürgisser, Johan Kjeldgaard-Pedersen, Peter Bro Miltersen

We study two quite different approaches to understanding the complexity

of fundamental problems in numerical analysis. We show that both hinge

on the question of understanding the complexity of the following problem,

which we call PosSLP:

Given a division-free straight-line program

producing an integer N, decide whether N>0.

more >>>

Ran Raz, Amir Shpilka, Amir Yehudayoff

We construct an explicit polynomial $f(x_1,...,x_n)$, with

coefficients in ${0,1}$, such that the size of any syntactically

multilinear arithmetic circuit computing $f$ is at least

$\Omega( n^{4/3} / log^2(n) )$. The lower bound holds over any field.

Rahul Santhanam

We show that for each k > 0, MA/1 (MA with 1 bit of advice) does not have circuits of size n^k. This implies the first superlinear circuit lower bounds for the promise versions of the classes MA, AM and ZPP_{||}^{NP}.

We extend our main result in several ways. For ... more >>>

Nutan Limaye, Meena Mahajan, B. V. Raghavendra Rao

The parallel complexity class NC^1 has many equivalent models such as

polynomial size formulae and bounded width branching

programs. Caussinus et al. \cite{CMTV} considered arithmetizations of

two of these classes, #NC^1 and #BWBP. We further this study to

include arithmetization of other classes. In particular, we show that

counting paths ...
more >>>

Zeev Dvir, Amir Shpilka, Amir Yehudayoff

In this paper we show that lower bounds for bounded depth arithmetic circuits imply derandomization of polynomial identity testing for bounded depth arithmetic circuits. More formally, if there exists an explicit polynomial f(x_1,...,x_m) that cannot be computed by a depth d arithmetic circuit of small size then there exists ... more >>>

Ran Raz

A basic fact in linear algebra is that the image of the curve

$f(x)=(x^1,x^2,x^3,...,x^m)$, say over $C$, is not contained in any

$m-1$ dimensional affine subspace of $C^m$. In other words, the image

of $f$ is not contained in the image of any polynomial-mapping

$G:C^{m-1} ---> C^m$ ...
more >>>

Ran Raz, Amir Yehudayoff

We prove an exponential lower bound for the size of constant depth multilinear arithmetic circuits computing either the determinant or the permanent (a circuit is called multilinear, if the polynomial computed by each of its gates is multilinear). We also prove a super-polynomial separation between the size of product-depth $d$ ... more >>>

Vikraman Arvind, Partha Mukhopadhyay, Srikanth Srinivasan

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 >>>

Meena Mahajan, B. V. Raghavendra Rao

Functions in arithmetic NC1 are known to have equivalent constant

width polynomial degree circuits, but the converse containment is

unknown. In a partial answer to this question, we show that syntactic

multilinear circuits of constant width and polynomial degree can be

depth-reduced, though the resulting circuits need not be ...
more >>>

Manindra Agrawal, V Vinay

We show that proving exponential lower bounds on depth four arithmetic

circuits imply exponential lower bounds for unrestricted depth arithmetic

circuits. In other words, for exponential sized circuits additional depth

beyond four does not help.

We then show that a complete black-box derandomization of Identity Testing problem for depth four ... more >>>

Neeraj Kayal, Shubhangi Saraf

We study depth three arithmetic circuits with bounded top fanin. We give the first deterministic polynomial time blackbox identity test for depth three circuits with bounded top fanin over the field of rational numbers, thus resolving a question posed by Klivans and Spielman (STOC 2001).

Our main technical result is ... more >>>

Zohar Karnin, Partha Mukhopadhyay, Amir Shpilka, Ilya Volkovich

We give the first sub-exponential time deterministic polynomial

identity testing algorithm for depth-$4$ multilinear circuits with

a small top fan-in. More accurately, our algorithm works for

depth-$4$ circuits with a plus gate at the top (also known as

$\Spsp$ circuits) and has a running time of

$\exp(\poly(\log(n),\log(s),k))$ where $n$ is ...
more >>>

Zeev Dvir

We describe a new approach for the problem of finding {\rm rigid} matrices, as posed by Valiant [Val77], by connecting it to the, seemingly unrelated, problem of proving lower bounds for locally self-correctable codes. This approach, if successful, could lead to a non-natural property (in the sense of Razborov and ... more >>>

Andreas Krebs, Nutan Limaye, Meena Mahajan

We give a \#NC$^1$ upper bound for the problem of counting accepting paths in any fixed visibly pushdown automaton. Our algorithm involves a non-trivial adaptation of the arithmetic formula evaluation algorithm of Buss, Cook, Gupta, Ramachandran (BCGR: SICOMP 21(4), 1992). We also show that the problem is \#NC$^1$ hard. Our ... more >>>

Scott Aaronson, Dieter van Melkebeek

We present an alternate proof of the result by Kabanets and Impagliazzo that derandomizing polynomial identity testing implies circuit lower bounds. Our proof is simpler, scales better, and yields a somewhat stronger result than the original argument.

more >>>Maurice Jansen

For two polynomials $f \in \mathbb{F}[x_1, x_2, \ldots, x_n, y]$ and $p \in \mathbb{F}[x_1, x_2, \ldots, x_n]$, we say that $p$ is a root of $f$, if $f(x_1, x_2, \ldots, x_n, p) \equiv 0$. We study the relation between the arithmetic circuit sizes of $f$ and $p$ for general circuits ... more >>>

Matthew Anderson, Dieter van Melkebeek, Ilya Volkovich

We present a polynomial-time deterministic algorithm for testing whether constant-read multilinear arithmetic formulae are identically zero. In such a formula each variable occurs only a constant number of times and each subformula computes a multilinear polynomial. Our algorithm runs in time $s^{O(1)}\cdot n^{k^{O(k)}}$, where $s$ denotes the size of the ... more >>>

Neeraj Kayal, Chandan Saha

The sum of square roots problem over integers is the task of deciding the sign of a nonzero sum, $S = \Sigma_{i=1}^{n}{\delta_i}$ . \sqrt{$a_i$}, where $\delta_i \in$ { +1, -1} and $a_i$'s are positive integers that are upper bounded by $N$ (say). A fundamental open question in numerical analysis and ... more >>>

Chandan Saha, Ramprasad Saptharishi, Nitin Saxena

Finding an efficient solution to the general problem of polynomial identity testing (PIT) is a challenging task. In this work, we study the complexity of two special but natural cases of identity testing - first is a case of depth-$3$ PIT, the other of depth-$4$ PIT.

Our first problem is ... more >>>

Malte Beecken, Johannes Mittmann, Nitin Saxena

Algebraic independence is an advanced notion in commutative algebra that generalizes independence of linear polynomials to higher degree. Polynomials $\{f_1,\ldots, f_m\} \subset \mathbb{F}[x_1,\ldots, x_n]$ are called algebraically independent if there is no non-zero polynomial $F$ such that $F(f_1, \ldots, f_m) = 0$. The transcendence degree, $\mbox{trdeg}\{f_1,\ldots, f_m\}$, is the maximal ... more >>>

Shubhangi Saraf, Ilya Volkovich

We study the problem of identity testing for multilinear $\Spsp(k)$ circuits, i.e. multilinear depth-$4$ circuits with fan-in $k$ at the top $+$ gate. We give the first polynomial-time deterministic

identity testing algorithm for such circuits. Our results also hold in the black-box setting.

The running time of our algorithm is ... more >>>

Guy Moshkovitz

In this paper we present a combinatorial approach for proving complexity lower bounds. We mainly focus on the following instantiation of it. Consider a pair of properties of $m$-edge regular hypergraphs. Suppose they are ``indistinguishable'' with respect to hypergraphs with $m-t$ edges, in the sense that every such hypergraph has ... more >>>

Ankit Gupta, Pritish Kamath, Neeraj Kayal, Ramprasad Saptharishi

We show that, over $\mathbb{C}$, if an $n$-variate polynomial of degree $d = n^{O(1)}$ is computable by an arithmetic circuit of size $s$ (respectively by an algebraic branching program of size $s$) then it can also be computed by a depth three circuit (i.e. a $\Sigma \Pi \Sigma$-circuit) of size ... more >>>

Oded Goldreich, Avi Wigderson

We propose that multi-linear functions of relatively low degree

over GF(2) may be good candidates for obtaining exponential

lower bounds on the size of constant-depth Boolean circuits

(computing explicit functions).

Specifically, we propose to move gradually from linear functions

to multilinear ones, and conjecture that, for any $t\geq2$,

more >>>

Mrinal Kumar, Shubhangi Saraf

We study the class of homogenous $\Sigma\Pi\Sigma\Pi(r)$ circuits, which are depth 4 homogenous circuits with top fanin bounded by $r$. We show that any homogenous $\Sigma\Pi\Sigma\Pi(r)$ circuit computing the permanent of an $n\times n$ matrix must have size at least $\exp\left(n^{\Omega(1/r)}\right)$.

In a recent result, Gupta, Kamath, Kayal and ... more >>>

Mrinal Kumar, Shubhangi Saraf

In recent years, a very exciting and promising method for proving lower bounds for arithmetic circuits has been proposed. This method combines the method of {\it depth reduction} developed in the works of Agrawal-Vinay [AV08], Koiran [Koi12] and Tavenas [Tav13], and the use of the shifted partial derivative complexity measure ... more >>>

Swastik Kopparty, Shubhangi Saraf, Amir Shpilka

In this paper we show that the problem of deterministically factoring multivariate polynomials reduces to the problem of deterministic polynomial identity testing. Specifically, we show that given an arithmetic circuit (either explicitly or via black-box access) that computes a polynomial $f(X_1,\ldots,X_n)$, the task of computing arithmetic circuits for the factors ... more >>>

Zeev Dvir, Rafael Mendes de Oliveira, Amir Shpilka

Two polynomials $f, g \in F[x_1, \ldots, x_n]$ are called shift-equivalent if there exists a vector $(a_1, \ldots, a_n) \in {F}^n$ such that the polynomial identity $f(x_1+a_1, \ldots, x_n+a_n) \equiv g(x_1,\ldots,x_n)$ holds. Our main result is a new randomized algorithm that tests whether two given polynomials are shift equivalent. Our ... more >>>

Neeraj Kayal, Chandan Saha

Shpilka and Wigderson (CCC 1999) had posed the problem of proving exponential lower bounds for (nonhomogeneous) depth three arithmetic circuits with bounded bottom fanin over a field $\mathbb{F}$ of characteristic zero. We resolve this problem by proving a $N^{\Omega(\frac{d}{\tau})}$ lower bound for (nonhomogeneous) depth three arithmetic circuits with bottom fanin ... more >>>

Eric Allender, Anna Gal, Ian Mertz

We consider arithmetic complexity classes that are in some sense dual to the classes VP(Fp) that were introduced by Valiant. This provides new characterizations of the complexity classes ACC^1 and TC^1, and also provides a compelling example of

a class of high-degree polynomials that can be simulated via arithmetic circuits ...
more >>>

Ankit Gupta

We present an algebraic-geometric approach for devising a deterministic polynomial time blackbox identity testing (PIT) algorithm for depth-4 circuits with bounded top fanin. Using our approach, we devise such an algorithm for the case when such circuits have bounded bottom fanin and satisfy a certain non-degeneracy condition. In particular, we ... more >>>

Rafael Mendes de Oliveira, Amir Shpilka, Ben Lee Volk

In this paper we give subexponential size hitting sets for bounded depth multilinear arithmetic formulas. Using the known relation between black-box PIT and lower bounds we obtain lower bounds for these models.

For depth-3 multilinear formulas, of size $\exp(n^\delta)$, we give a hitting set of size $\exp(\tilde{O}(n^{2/3 + 2\delta/3}))$. ... more >>>

Neeraj Kayal, Chandan Saha

In a multi-$k$-ic depth three circuit every variable appears in at most $k$ of the linear polynomials in every product gate of the circuit. This model is a natural generalization of multilinear depth three circuits that allows the formal degree of the circuit to exceed the number of underlying variables ... more >>>

Ilya Volkovich

In Arithmetic Circuit Complexity the standard operations are $\{+,\times\}$.

Yet, in some scenarios exponentiation gates are considered as well (see e.g. \cite{BshoutyBshouty98,ASSS12,Kayal12,KSS14}).

In this paper we study the question of efficiently evaluating a polynomial given an oracle access to its power.

That is, beyond an exponentiation gate. As ...
more >>>

Benny Applebaum, Jonathan Avron, Christina Brzuska

We study the possibility of computing cryptographic primitives in a fully-black-box arithmetic model over a finite field F. In this model, the input to a cryptographic primitive (e.g., encryption scheme) is given as a sequence of field elements, the honest parties are implemented by arithmetic circuits which make only a ... more >>>

Mrinal Kumar, Shubhangi Saraf

We study the complexity of representing polynomials as a sum of products of polynomials in few variables. More precisely, we study representations of the form $$P = \sum_{i = 1}^T \prod_{j = 1}^d Q_{ij}$$

such that each $Q_{ij}$ is an arbitrary polynomial that depends on at most $s$ variables.

Mrinal Kumar, Ramprasad Saptharishi

In this paper, we show exponential lower bounds for the class of homogeneous depth-$5$ circuits over all small finite fields. More formally, we show that there is an explicit family $\{P_d : d \in N\}$ of polynomials in $VNP$, where $P_d$ is of degree $d$ in $n = d^{O(1)}$ variables, ... more >>>

Ilya Volkovich

An \emph{arithmetic circuit} is a directed acyclic graph in which the operations are $\{+,\times\}$.

In this paper, we exhibit several connections between learning algorithms for arithmetic circuits and other problems.

In particular, we show that:

\begin{enumerate}

\item Efficient learning algorithms for arithmetic circuit classes imply explicit exponential lower bounds.

Fu Li, Iddo Tzameret, Zhengyu Wang

Does every Boolean tautology have a short propositional-calculus proof? Here, a propositional-calculus (i.e., Frege) proof is any proof starting from a set of axioms and deriving new Boolean formulas using a fixed set of sound derivation rules. Establishing any super-polynomial size lower bound on Frege proofs (in terms of the ... more >>>

Eric Allender, Asa Goodwillie

We continue the study of the complexity classes VP(Zm) and LambdaP(Zm) which was initiated in [AGM15]. We distinguish between “strict” and “lax” versions of these classes and prove some new equalities and inclusions between these arithmetic circuit classes and various subclasses of ACC^1.

more >>>Neeraj Kayal, Vineet Nair, Chandan Saha

We show an exponential separation between two well-studied models of algebraic computation, namely read-once oblivious algebraic branching programs (ROABPs) and multilinear depth three circuits. In particular we show the following:

1. There exists an explicit $n$-variate polynomial computable by linear sized multilinear depth three circuits (with only two product gates) ... more >>>

Neeraj Kayal, Chandan Saha, Sébastien Tavenas

Let $r \geq 1$ be an integer. Let us call a polynomial $f(x_1, x_2,\ldots, x_N) \in \mathbb{F}[\mathbf{x}]$ as a multi-$r$-ic polynomial if the degree of $f$ with respect to any variable is at most $r$ (this generalizes the notion of multilinear polynomials). We investigate arithmetic circuits in which the output ... more >>>

Mrinal Kumar, Shubhangi Saraf

In recent years there has been a flurry of activity proving lower bounds for

homogeneous depth-4 arithmetic circuits [GKKS13, FLMS14, KLSS14, KS14c], which has brought us very close to statements that are known to imply VP $\neq$ VNP. It is a big question to go beyond homogeneity, and in ...
more >>>

C Ramya, Raghavendra Rao B V

We study limitations of polynomials computed by depth two circuits built over read-once polynomials (ROPs) and depth three syntactically multi-linear formulas.

We prove an exponential lower bound for the size of the $\Sigma\Pi^{[N^{1/30}]}$ arithmetic circuits built over syntactically multi-linear $\Sigma\Pi\Sigma^{[N^{8/15}]}$ arithmetic circuits computing a product of variable ...
more >>>

Meena Mahajan, Raghavendra Rao B V, Karteek Sreenivasaiah

Polynomial Identity Testing (PIT) algorithms have focused on

polynomials computed either by small alternation-depth arithmetic circuits, or by read-restricted

formulas. Read-once polynomials (ROPs) are computed by read-once

formulas (ROFs) and are the simplest of read-restricted polynomials.

Building structures above these, we show the following:

\begin{enumerate}

\item A deterministic polynomial-time non-black-box ...
more >>>

Neeraj Kayal, Chandan Saha, Sébastien Tavenas

We show an $\Omega \left(\frac{n^3}{(\ln n)^2}\right)$ lower bound on the size of any depth three ($\SPS$) arithmetic circuit computing an explicit multilinear polynomial in $n$ variables over any field. This improves upon the previously known quadratic lower bound by Shpilka and Wigderson.

more >>>Michael Forbes, Mrinal Kumar, Ramprasad Saptharishi

We say that a circuit $C$ over a field $F$ functionally computes an $n$-variate polynomial $P \in F[x_1, x_2, \ldots, x_n]$ if for every $x \in \{0,1\}^n$ we have that $C(x) = P(x)$. This is in contrast to {syntactically} computing $P$, when $C \equiv P$ as formal polynomials. In this ... more >>>

Suryajith Chillara, Mrinal Kumar, Ramprasad Saptharishi, V Vinay

Agrawal and Vinay [AV08] showed how any polynomial size arithmetic circuit can be thought of as a depth four arithmetic circuit of subexponential size. The resulting circuit size in this simulation was more carefully analyzed by Korian [Koiran] and subsequently by Tavenas [Tav13]. We provide a simple proof of this ... more >>>

Nikhil Balaji, Nutan Limaye, Srikanth Srinivasan

In this note, we prove that there is an explicit polynomial in VP such that any $\Sigma\Pi\Sigma$ arithmetic circuit computing it must have size at least $n^{3-o(1)}$. Up to $n^{o(1)}$ factors, this strengthens a recent result of Kayal, Saha and Tavenas (ICALP 2016) which gives a polynomial in VNP with ... more >>>

C Ramya, Raghavendra Rao B V

An n-variate Vandermonde polynomial is the determinant of the n × n matrix where the ith column is the vector (1, x_i , x_i^2 , . . . , x_i^{n-1})^T. Vandermonde polynomials play a crucial role in the in the theory of alternating polynomials and occur in Lagrangian polynomial interpolation ... more >>>

Mrinal Kumar, Ben Lee Volk

We prove a lower bound of $\Omega(n^2/\log^2 n)$ on the size of any syntactically multilinear arithmetic circuit computing some explicit multilinear polynomial $f(x_1, \ldots, x_n)$. Our approach expands and improves upon a result of Raz, Shpilka and Yehudayoff [RSY08], who proved a lower bound of $\Omega(n^{4/3}/\log^2 n)$ for the same ... more >>>

Nathanael Fijalkow, Guillaume Lagarde, Pierre Ohlmann

This paper studies lower bounds for arithmetic circuits computing (non-commutative) polynomials. Our conceptual contribution is an exact correspondence between circuits and weighted automata: algebraic branching programs are captured by weighted automata over words, and circuits with unique parse trees by weighted automata over trees.

The key notion for understanding the ... more >>>

Vishwas Bhargava, Shubhangi Saraf, Ilya Volkovich

We present a deterministic algorithm for reconstructing multilinear $\Sigma\Pi\Sigma\Pi(k)$ circuits, i.e. multilinear depth-$4$ circuits with fan-in $k$ at the top $+$ gate. For any fixed $k$, given black-box access to a polynomial $f \in \mathbb{F}[x_{1},x_{2},\ldots ,x_{n}]$ computable by a multilinear $\Sigma\Pi\Sigma\Pi(k)$ circuit of size $s$, the algorithm runs in time ... more >>>

Pranjal Dutta, Gorav Jindal, Anurag Pandey, Amit Sinhababu

Given polynomials $f,g,h\,\in \mathbb{F}[x_1,\ldots,x_n]$ such that $f=g/h$, where both $g$ and $h$ are computable by arithmetic circuits of size $s$, we show that $f$ can be computed by a circuit of size $\poly(s,\deg(h))$. This solves a special case of division elimination for high-degree circuits (Kaltofen'87 \& WACT'16). The result ... more >>>