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NP-hardness of solving systems of *homogeneous* polynomial equations

It is well-known that deciding if a system of quadratic polynomial equations in several variables admits a solution in a finite field is NP-complete. There is a simple reduction from 3SAT, that works ...
Charles Bouillaguet's user avatar
0 votes
0 answers
25 views

Multiplying two bivariate polynomials using FFT for univariate polynomials multiplication

Let $$f(x,y)=\sum_{0\le i\le n , 0 \le j \le d}a_{i,j}x^iy^j$$ $$g(x,y)=\sum_{0\le i\le n , 0 \le j \le d}b_{i,j}x^iy^j$$ We want to multiply $f g$. I did the following: $$f(x,x^{2n+1})=\sum_{0\le i\...
AlgoMan's user avatar
1 vote
1 answer
22 views

Best internal representation of a random variable to enable iterative sampling and interpolation/regression

Let $[0,100]$ denote the interval of real numbers between $0$ and $100$. Given a function $f:[0,100]^n \rightarrow \mathbb{R}^+$, I want to implement the following simple algorithm to search for the ...
EXPTIME-complete's user avatar
1 vote
0 answers
88 views

What is the difference between $O$ and $\widetilde{O}$?

We know that $\widetilde{O}(f(n))$ — $O$ with a tilde above it — which means $O(f(n) \text {polylog}(f(n)))$, i.e., $O(f(n) (\log f(n))^k)$ for some $k$. Also I have seen in Wikipedia that $n2^n=\...
A. H.'s user avatar
  • 498
1 vote
1 answer
34 views

Distinction between square roots in cyclic fields

Let $\mathbb{F}=\mathbb{Z}/p\mathbb{Z}$ a cyclic field. Where $p$ is fixed Let $(H)_{n\in\mathbb{N}} \in \mathbb{Z}[x_1,\dots]^{\mathbb{N}}$ a family of polynomials with $H_n\in \mathbb{Z}[x_1,\dots,...
Rami Zouari's user avatar
0 votes
1 answer
56 views

Sumcheck protocol - how are these 2 polynomials different?

I am going through Justin Thaler's book - https://people.cs.georgetown.edu/jthaler/ProofsArgsAndZK.pdf - "Proofs, Arguments, and Zero-Knowledge" He is describing the Sumcheck Protocol on ...
user93353's user avatar
  • 125
2 votes
0 answers
135 views

Optimal reassociations is NP-hard?

Consider signed integers with common addition and multiplication. Reassociation of expression is another equivalent form. Say expressions: ...
Konstantin Vladimirov's user avatar
0 votes
1 answer
38 views

Which one grows faster, an exponential function where the exponent grows faster than logarithmic or a factorial powered by n?

Which function grows faster: $$f(n) = 4^{n^2 \log_2 n} \text{ or } g(n) = (n!)^n$$ Which is true? $f(n) = O(g(n))$ $g(n) = O(f(n))$ i.e., $f(n) = \Theta(g(n))$ none of the above? For lower values of ...
Kong's user avatar
  • 1
0 votes
0 answers
49 views

Progress towards a Polynomial time factoring algorithm?

This is probably insignificant, but I was messing around with polynomials, and found out that, if we have a number, n = pq that we want to factor, if we expand (k+1)^n -k^n - 1, mod n, the first ...
Colonizor48's user avatar
0 votes
2 answers
85 views

Polynomial representations of Boolean functions

The AND boolean function $AND(x)$ can be represented using the polynomial $P(x) = x_1x_2\cdots x_n$. I have a few questions: Is there a similar polynomial for the PARITY boolean function? Is there a ...
user avatar
1 vote
1 answer
64 views

product of every difference

Given a sorted array where every element is distinct, we need to evaluate product of every difference, modulo $ 10^9 + 7 $ $$ \prod_{i < j} (arr[j] - arr[i]) \% (10^9 + 7) $$ Best approach I can ...
bihariforces's user avatar
2 votes
0 answers
56 views

Algorithm to compute sum of quotient polynomials

Let $f(X)$ be a polynomial in $\mathbb{F}_p[X]$ for some prime $p$ (of size 256 bits) that is not necessarily FFT-friendly. Let $a_1,\cdots,a_n$, $b_1,\cdots, b_n$ be $\mathbb{F}_p$ elements. What is ...
Mathdropout's user avatar
1 vote
2 answers
67 views

Subquadratic multiplication of polynomials in the max-plus/tropical semiring

Is there an algorithm to multiply two polynomials with coefficients in the max-plus semiring $(\mathbb{Z}\cup\{-\infty\}, \max, +)$ which is faster than the trivial one? I'm interested in the ...
ant_arctic's user avatar
0 votes
1 answer
78 views

O(nlogn)-time complexity

Is there a $O(nlogn)$ time algorithm for computing $p(x)=\sum\limits_{i=0}^na_ix^i$ ? I think with the method below I get O(n), but I need O(nlogn) Hint: there's a way to calculate $x^i$ more ...
R.Jean's user avatar
  • 3
0 votes
1 answer
69 views

Algorithm for determining an algebraic positivity property of a multivariate polynomial

I am considering multivariate polynomials with integer coefficients that can be expressed as sums of products of terms of the form $y_i-z_j$ for positive integers $i$ and $j$. I am trying to find an ...
Matt Samuel's user avatar
1 vote
0 answers
47 views

What algorithms apart from FFT get a computational boost by leveraging complex numbers?

If we think of the algorithmic problem of doing a convolution of two arrays, it turns out that converting them to the frequency domain first and then doing an element-wise product is equivalent. And ...
Rohit Pandey's user avatar
0 votes
1 answer
50 views

Can an arithmetic circuit have multiple outputs?

An arithmetic circuit relates to calculating the value of a polynomial given some inputs. But is it still considered a circuit if the DAG corresponds to the evaluation of multiple polynomials that ...
Thorkil Værge's user avatar
2 votes
0 answers
82 views

Fastest algorithm for polynomial multiplication in 256-bit finite fields

I am looking for the fastest algorithm (in practice) to multiply two polynomials $f(X)\cdot h(X)$ in $\mathbb{F}_p[X]$. The prime $p$ is roughly $256$ bits but the integer $p-1$ might not have any ...
Mathdropout's user avatar
1 vote
1 answer
103 views

Complexity of multiplying bivariate polynomials of degree n

Let $P(X,Y)$ and $Q(X,Y)$ be two bivariate polynomials of degree at most $n$. Using $O(n^2)$ FFTs, we can compute the product $PQ$ in time $O(n^3\log n)$. Q: Is there a faster algorithm to compute $PQ$...
GBathie's user avatar
  • 642
1 vote
0 answers
25 views

Time and Space Complexity of Isolating the Roots of a Polynomial

Can someone provide a list of references of papers, books, etc. presenting results on the time and space complexity of the problem of isolating the roots of a univariate polynomial $P(t)$ with integer ...
Miquel Ramirez's user avatar
1 vote
0 answers
170 views

What's the fastest algorithm for polynomial interpolation in finite field with prime order at points 1, 2, 3, ..., n?

Suppose we have finite field $\mathbb{F}_p$ with prime order $p$. Can we find polynomial in $\mathbb{F}_p[x]$ having given values $a_1, a_2, ... a_n$ at $x=1, 2, ..., n$ in less than $O(n^2)$ ...
Somnium's user avatar
  • 275
4 votes
0 answers
60 views

Polynomial multiplication in finite field without smooth-order roots of unity

I am working in a finite prime field $\mathbb{F}_p$ that does not have primitive $n$-th roots of unity for any large smooth integer $n$, which makes FFTs a bit difficult. If I need to compute a ...
Mathdropout's user avatar
2 votes
3 answers
631 views

Deciding whether an integer polynomial has an integer root

This is a question written by my instructor Z. Loria . Consider the following problem: Given a polynomial $p(x) = \sum_{i=0}^n a_ix^i$, where $a_i$ are integers, is there a natural number $n \in \...
RedYoel's user avatar
  • 217
2 votes
1 answer
169 views

Does the reliability of polynomial hashing depend on whether the modulus is prime, for coprime base and modulus?

A polynomial hash of a string $s$ with base $b$ and modulus $M$ is defined as $$ H(s) = (s_0 + s_1 b + s_2 b^2 + \dots + s_{n-1} b^{n-1}) \mod M. $$ I have proven (and this is quite obvious) that ...
Alisa Sireneva's user avatar
2 votes
1 answer
51 views

Is there a simplistic way of describing the proof to the undecidability of David Hilbert's 10th problem?

I recently have been reading a bunch about David Hilbert's famous 10th problem, and trying to understand its proof. I am currently in the process of reading through an explanation of the proof, given ...
David Jentjens's user avatar
1 vote
0 answers
48 views

Efficient bit-level implementation of Boolean polynomials with few variables

A Boolean polynomial in $n$ variables $x_1, \dots, x_n$ is an expression of the form $$\sum_{\mathbf{s} \in \{0,1\}^n} c_{\mathbf{s}} x_1^{s_1} \cdots x_n^{s_n}, \quad \text{ where } c_s \in \{0,1\} .$...
BubbleZ's user avatar
  • 11
0 votes
0 answers
42 views

From roots to coefficients of a polynomial [duplicate]

Polynomials are usually written as a sum of powers (or various products of generators) and Google gives me lots of results on how to get from that to the form that is a product of degree-$1$ ...
John's user avatar
  • 121
0 votes
1 answer
132 views

Finding $Aeven(x)$ and $Aodd(x)$ for a Fast Fourier Transform (FFT) problem?

In this article about FFT the author used FFT on this polynomial. $A(x) = 3+2x+3x^2+4x^3$ Using $ A(x)= Aeven(x^2) + xAodd(x^2)$ the author determined the following for $Aeven(x)$ and $Aodd(x)$ $ ...
calico jack's user avatar
-1 votes
1 answer
22 views

Given x find a polynomial such that pol(x)=a for a known a?

You are given x,a. Find a polynomial p(y) with the leading coafficent 1 such that p(x)=a. How to write an algorithem to solve this efficently? I have no idea where to start
sean python's user avatar
1 vote
0 answers
62 views

Finding points of local maximum error in Remez algorithm

So the Remez algorithm is an algorithm for finding optimal polynomial approximations or at the very least for converging towards them. To find an approximation of $f$ by an $N$th degree polynomial the ...
Jake's user avatar
  • 3,800
3 votes
1 answer
198 views

Computing coefficients of $p(x)^n$ in time $O(n \log n)$

For homework I've to give an algorithm that computes the coefficients of the polynomial $p(x)^n$ in time $O(n\log n)$, where $p(x)$ is a polynomial of degree 7. As an hint I'm told to consider first ...
RedYoel's user avatar
  • 217
0 votes
0 answers
53 views

Time to evaluate a product of binomials $1 + x^i$

I am considering the asymptotic analysis required to convert a polynomial of the shape $$P(x) = \prod_{i = 1}^{n}(1 + x^{s_i})$$ to its "full" representation, for example $$P(x) = 1+x^3+x^5+...
Mikkel Andersen's user avatar
0 votes
1 answer
320 views

Multiplication of polynomials in value representation as done for Fast Fourier Transform

I am trying to understand the discrete Fast Fourier Transform. I get the idea of switching between coefficient and value representations to and then back but I am stuck in figuring out how the ...
heretoinfinity's user avatar
1 vote
0 answers
97 views

Optimize binary multivariate polynomial multiplication

You have a few variables that can only assume the values 0 or 1 and you use those to form two polynomials. Is there a way to multiply the two polynomials that is faster than O(n²) where n is the ...
Victor Marcelino's user avatar
1 vote
1 answer
85 views

How polynomial interpolation of polynomial multiplication algorithm works?

I'm trying to apply the following algorithm from DPV's textbook to an example to see how it works. First, the algorithm is as following: Algorithm [DPV, p. 60] Input: Coefficients of two polynomials. ...
user777's user avatar
  • 749
1 vote
0 answers
68 views

Express polynomial as sum of two lower-degree polynomials, modulo another

Suppose I have a polynomial $p(x)$, and a "modulus" polynomial $q(x)$ of degree $d$. I want to find two polynomials $r_1(x),r_2(x)$ of degree $\le d_1,d_2$ such that $$p(x) \equiv r_1(x) x^...
D.W.'s user avatar
  • 162k
2 votes
0 answers
120 views

Decide whether a polynomial has a root

Let $A$ be a ring such that all elements of $A$ are complex computable numbers. I'm interested in knowing whether the decision problem that asks, given $P\in A[X]$, if $P$ has a root in $A$ is ...
Rémi's user avatar
  • 402
1 vote
2 answers
66 views

Show that the OR of n variables cannot be expressed as a polynomial over Fp of degree less than n

Here is a question from Computational Complexity by Arora and Barak: Show that representing OR of $n$ variables $x_1,x_2,\dots,x_n$ exactly over a polynomial in $GF(q)$ requires degree exactly $n$. (...
roydiptajit's user avatar
1 vote
0 answers
38 views

Binomial basis and the usual basis of polynomial algebra $\mathbb C(X)$

Consider the polynomial algebra $\mathbb C[X]$. Then the set $\{1, X, X^2,\dots,\}$ forms a vector space basis for this algebra. In general, we know that the set $\{P_n(X) \in \mathbb C[X]: n \ge 0 \...
GA316's user avatar
  • 111
0 votes
1 answer
52 views

Represent a DNF formula as a multivariate linear formula?

Lets say I have the following DNF: (x or y) and (z or i) / $(x\lor y)\land(z\lor i)$ How do I convert that into a polynomial form?
Michael's user avatar
1 vote
0 answers
45 views

How do I decode a received polynomial code with an error?

As a message I get (5,0,1,3), which is coding a sequence of numbers of length 2 in $\mathbb{F}_7$ as polynom with the 4 support points a1 = 0, a2 = 1, a3 = 2, a4 = 6. In the transimission occured an ...
Rapiz's user avatar
  • 21
1 vote
1 answer
194 views

Given an array $a$, we have to find product of $a_{j}$-$a_{i}$ modulo $998244353$ over all $i$ and $j$ given $j>i$

Given an array $a$, we have to find product of $a_{j}$-$a_{i}$ modulo $998244353$ over all $i$ and $j$ given $j>i$. For eg. Let the array be $1,2,3$ then my answer will be calculated as- $(2-1)$.$(...
Viplaw Srivastava's user avatar
2 votes
0 answers
222 views

Understanding CRC Computation with PCLMULQDQ

I am currently reading this paper which shows how to calculate CRC using the instruction PCLMULQDQ. I don't quite understand the equations in it yet. Starting with this one for the definition of ...
Paul Schaaf's user avatar
3 votes
1 answer
234 views

Is deciding solvability of systems of quadratic equations with integer coefficients over the reals in NP?

In the book 'Computational Complexity' by Arora and Barak the following question is posed (exercise 2.20.): Let REALQUADEQ be the language of all satisfiable sets of quadratic equations over real ...
mwien's user avatar
  • 33
1 vote
0 answers
64 views

How to compute the first n coefficients using number theoretic transform (NTT)?

I need to find the first $n$ coefficients of $$\prod_{i = 1}^{i = q}(1 + x^{a_i})^{b_i}$$ modulo a NTT favourable prime. Can someone suggest an algorithm with worst-case complexity $O(n\log n)$ or $O(...
Nick Ger's user avatar
2 votes
1 answer
213 views

Why does $x^{15}+x^{14}+1$ detect all errors at most 32768 bits apart?

Reference Question from Forouzon Book Computer Network. Find the status of the following generator related to two isolated, single-bit errors. $$x^{15} + x^{14} + 1$$ Answer given : This polynomial ...
Piyush Sawarkar's user avatar
3 votes
0 answers
29 views

Bit complexity of computing the sign of an expression evaluated at an algebraic number

I have a univariate polynomial $F(t)\in \mathbb{Z}[t]$ of degree $d$ and maximum bitsize of coefficients equal to $\tau$ and $G(t) \in \mathbb{Z}[t]$ of degree $d^2$ and maximum bitsize of ...
asdf's user avatar
  • 131
3 votes
1 answer
462 views

Is O(n log n) exponential speedup over O(n^2)?

I would like to know if $O(n \log n)$ is an exponential speedup over $O(n^2)$?
Rascalniikov's user avatar
0 votes
0 answers
306 views

Multiplying bivariate polynomials using FFT

Consider two bivariate polynomials of degree at most $n-1$ in each variable: $$ F(x,y) = \sum_{i,j=0}^{n-1} f_{i,j} x^i y^j \quad \text{and} \quad G(x,y) = \sum_{i,j=0}^{n-1} g_{i,j} x^i y^j. $$ ...
lan's user avatar
  • 1
15 votes
2 answers
4k views

What is the most efficient algorithm to compute polynomial coefficients from its roots?

Given $n$ roots, $x_1, x_2, \dotsc, x_n$, the corresponding monic polynomial is $$y = (x-x_1)(x-x_2)\dotsm(x-x_n) = \prod_{i}^n (x - x_i)$$ To get the coefficients, i.e., $y = \sum_{i}^n a_i x^i$, a ...
xucheng's user avatar
  • 253