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REPORTS > KEYWORD > ITERATED MATRIX MULTIPLICATION:
Reports tagged with Iterated Matrix Multiplication:
TR11-083 | 22nd May 2011
Eric Allender, Fengming Wang

#### On the power of algebraic branching programs of width two

We show that there are families of polynomials having small depth-two arithmetic circuits that cannot be expressed by algebraic branching programs of width two. This clarifies the complexity of the problem of computing the product of a sequence of two-by-two matrices, which arises in several
settings.

more >>>

TR13-028 | 14th February 2013
Mrinal Kumar, Gaurav Maheshwari, Jayalal Sarma

#### Arithmetic Circuit Lower Bounds via MaxRank

We introduce the polynomial coefficient matrix and identify maximum rank of this matrix under variable substitution as a complexity measure for multivariate polynomials. We use our techniques to prove
super-polynomial lower bounds against several classes of non-multilinear arithmetic circuits. In particular, we obtain the following results :

$\bullet$ As ... more >>>

TR15-154 | 22nd September 2015
Neeraj Kayal, Vineet Nair, Chandan Saha

#### Separation between Read-once Oblivious Algebraic Branching Programs (ROABPs) and Multilinear Depth Three Circuits

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 >>>

TR15-181 | 13th November 2015
Neeraj Kayal, Chandan Saha, Sébastien Tavenas

#### On the size of homogeneous and of depth four formulas with low individual degree

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 >>>

TR17-021 | 11th February 2017
Neeraj Kayal, Vineet Nair, Chandan Saha, Sébastien Tavenas

#### Reconstruction of full rank Algebraic Branching Programs

An algebraic branching program (ABP) A can be modelled as a product expression $X_1\cdot X_2\cdot \dots \cdot X_d$, where $X_1$ and $X_d$ are $1 \times w$ and $w \times 1$ matrices respectively, and every other $X_k$ is a $w \times w$ matrix; the entries of these matrices are linear forms ... more >>>

TR17-034 | 21st February 2017
Karl Bringmann, Christian Ikenmeyer, Jeroen Zuiddam

#### On algebraic branching programs of small width

Revisions: 1

In 1979 Valiant showed that the complexity class VP_e of families with polynomially bounded formula size is contained in the class VP_s of families that have algebraic branching programs (ABPs) of polynomially bounded size. Motivated by the problem of separating these classes we study the topological closure VP_e-bar, i.e. the ... more >>>

TR21-081 | 14th June 2021
Nutan Limaye, Srikanth Srinivasan, Sébastien Tavenas

#### Superpolynomial Lower Bounds Against Low-Depth Algebraic Circuits

Revisions: 1

An Algebraic Circuit for a polynomial $P\in F[x_1,\ldots,x_N]$ is a computational model for constructing the polynomial $P$ using only additions and multiplications. It is a \emph{syntactic} model of computation, as opposed to the Boolean Circuit model, and hence lower bounds for this model are widely expected to be easier to ... more >>>

TR21-094 | 6th July 2021
Nutan Limaye, Srikanth Srinivasan, Sébastien Tavenas

#### New Non-FPT Lower Bounds for Some Arithmetic Formulas

An Algebraic Formula for a polynomial $P\in F[x_1,\ldots,x_N]$ is an algebraic expression for $P(x_1,\ldots,x_N)$ using variables, field constants, additions and multiplications. Such formulas capture an algebraic analog of the Boolean complexity class $\mathrm{NC}^1.$ Proving lower bounds against this model is thus an important problem.

It is known that, to prove ... more >>>

TR21-105 | 22nd July 2021
Suryajith Chillara

#### Functional lower bounds for restricted arithmetic circuits of depth four

Recently, Forbes, Kumar and Saptharishi [CCC, 2016] proved that there exists an explicit $d^{O(1)}$-variate and degree $d$ polynomial $P_{d} \in VNP$ such that if any depth four circuit $C$ of bounded formal degree $d$ which computes a polynomial of bounded individual degree $O(1)$, that is functionally equivalent to $P_d$, then ... more >>>

TR22-149 | 7th November 2022
Gil Cohen, Dean Doron, Ori Sberlo, Amnon Ta-Shma

#### Approximating Iterated Multiplication of Stochastic Matrices in Small Space

Matrix powering, and more generally iterated matrix multiplication, is a fundamental linear algebraic primitive with myriad applications in computer science. Of particular interest is the problem's space complexity as it constitutes the main route towards resolving the $\mathbf{BPL}$ vs. $\mathbf{L}$ problem. The seminal work by Saks and Zhou (FOCS 1995) ... more >>>

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