Questions tagged [factorization]
For questions about factorization, the decomposition of mathematical objects (e.g. natural numbers, polynomials) into products of smaller objects (e.g. primes, lower degree polynomials).
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questions with no upvoted or accepted answers
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Do the coefficients of these irreducible polynomials always become periodic?
Fix $n\in\mathbb N$ and a starting polynomial (or seed) $p_n=a_0+a_1x+\dots+a_nx^n$ with $a_k\in\mathbb Z\ \forall k$ and $a_0a_n\ne0$.
Define $p_{n+1},p_{n+2},\dots$ recursively by $p_r = p_{r-1}+...
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Are there efficient algorithms to factorise in $\mathbb{N}[X]$?
One way to do factorisation in $\mathbb{N}[X]$ is to use an algorithm to factorise in $\mathbb{Z}[X]$ and then to combine some factor to find a factorisation in $\mathbb{N}[X]$. Note that the ...
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A factorization game
This is a toy version of a problem I have posted recently.
Imagine playing the following game. You choose a polynomial $B$ over a finite field $\mathbb F_p$, of degree $\deg B\le p-1$ (where $p$ is a ...
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Factor-counting sequence
Define a non-negative integer sequence $\{\mathcal{F}_n\}$ as follows: start with 1 and, at each step, insert the number of entries already present in the sequence which are factors of the last one.
...
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Optimal Gear Trains
Suppose you need to slow down a turning motor so that a gear turns at
an angular velocity $\frac{a}{b}$ of that of the motor shaft, where $a$ and
$b$ are natural numbers. For example, this set of ...
6
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$p^2+a^2$ can be a squarefree number with all prime divisors less than $p$?
Let $p$ be a prime $\ge 31$.
Is there an integer $a < p$ such that $p^2 + a^2$ is a squarefree and all of its prime divisors are less than $p$?
For example, for $p=31$, $31^2+5^2 = 986 = 2 \times ...
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Reducibility of $f(x)^{2^n}+1$ and $f(x)^{2^n}+g(x)^{2^n}$
Related to generalized Fermat numbers.
Let $f(x),g(x)$ be coprime polynomials with integer coefficients.
Assume that if $f(x)$ or $g(x)$ are of the form $h(x)^k$ then $k$ is power
of two.
Q1 Is it ...
5
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455
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Factorizations as a product of primes minus one
Let $x$ be a positive rational number. I am interested in factorizing $x$ as a product of primes minus one. In fact, I would also like make sure the primes in the decomposition are distinct, and I ...
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Consecutive integers each of which has a large prime factor
There are many results about consecutive integers all having small prime factors. But what about consecutive integers each of which has a large prime factor?
More precisely, let $P(n)$ be the ...
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On factorization algorithms for $\mathcal{O}[x]$
We know that $\mathsf{LLL}$ algorithm provides factorization procedure that runs in poly time for polynomials in $\Bbb Z[x]$ that are primitive.
What other rings $\mathcal{O}$ can we use instead of $\...
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Least Prime Factor in a sequence of 2n consecutive integers
I was thinking about consecutive integers and I wondered if anyone had done work exploring whether a sequence of $2n$ consecutive integers (i.e. 101,102,103,...,100+2n) always contains at least one ...
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Has anyone studied factoring as a CO-product?
In factorization, like integer factorization, you start with an integer and end up with a kind-of list of pairs of other elements, namely the factors.
I want to explore the "Co-ness" of this....
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weak factorization systems (co)generated by an arbitrary class of morphisms
Under what assumptions can one prove existence of weak factorization systems (co)generated by a class of morphisms ?
Are there counterexamples ? I am interested both in assumptions on the class of ...
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Characterizing atomicity in a commutative domain
In Proposition 1.1 of [Math. Proc. Cambridge Phil. Soc. 64 (1968), No. 2, 251-264], P.M. Cohn famously claimed (without proof) that a commutative domain is atomic if and only if it satisfies the ...
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Near Pochhammer symbols: the equation $(n)_m-(k)_l=2$ for integers greater than or equal to two
In this post I consider the following equation involving Pochhammer symbols,
$$(n)_m-(k)_l=2\tag{1}$$
for positive integers $n\geq 2$ and $k\geq 2$, and positive integers $m\geq 2$ and $l\geq 2$.
...
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Can we efficiently factor $n$ given that $n=pq$ where $p,q$ are primes satisfying $p=a^2+b^2, q=2ab+1$ for some $a,b$
Suppose we're given a particular number $n \in \mathbb{N}$.
We're also given that $n=pq$ where $p,q$ are unknown primes satisfying
$$
p=a^2+b^2
$$ and
$$
q=2ab+1
$$
for some $a,b$.
Is there an ...
4
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Finding Rational Curves on a Surface
Let the field of rational numbers be our base field $k$. I hope to find all rational curves on the following surface $S$ defined by $f$. You can find the motivation in the end.
$f= (x^2y^2)z^3 + (5x^...
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Unique factorization for the semigroup generated by {2cos(π/n) | n>3}?
Let $S$ be the multiplicative semigroup of numbers generated by $B=\{ 2cos(\frac{\pi}{n}) \mid n \ge 4 \}$.
Question: Does every number of $S$ factorize uniquely (up to perm.) as a product of ...
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Possible $\mathsf{NP}$ complete problem from number theory
A candidate $\mathsf{NP}$ complete variant of factoring was posted in https://cstheory.stackexchange.com/questions/4769/an-np-complete-variant-of-factoring, where decision problem $\text{BOUNDED-...
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Analog of Euler's factoring technique
Is there an analog of Euler's Two Squares factoring theorem over polynomial rings $\Bbb Z[x]$ by considering a version for non-negative polynomials?
Euler's two squares factoring states that numbers ...
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More 3-connected cubic graphs with all 2-factors of same cycle type?
The setup is as in this question: Let $G$ be a 3-connected cubic graph. If all 2-factors of $G$ are isomorphic (as graphs), i.e. all have the same partition $\pi$ as cycle type, we'll say that $G$ is ...
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Efficiently factorize a KKT system with block diagonal upper corner
I have a system resulting from a quadratic energy minimization with linear equality constraints enforced with Lagrange multipliers which has the form:
\begin{equation}
A =
\left[\begin{array}{c|c}
\...
3
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answers
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Could a quantum computer factor $N=p\times q$ using Hadamard transforms on $x^2\bmod N$ (instead of Fourier transforms on $a^x\bmod N$)?
In Classically verifiable quantum advantage from a computational Bell test, Kahanamoku-Meyer, Choi, Vazirani, and Yao propose using $x^2 \bmod N$ in an interactive proof-of-quantumness. This is a two-...
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Atomicity and BF-ness in monoids of integer points of a polyhedral cone of $\mathbb R^n$
Fix an integer $n \ge 2$ and let $H$ be the (additive) monoid of integer points of a polyhedral cone of the Euclidean space $\mathbb R^n$ with the additional property that $H \setminus \{0_n\}$ is ...
3
votes
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Order of elements $\gamma$ and $1-\gamma$ in $\mathbb{F}_q$
I'd like to find if possible the orders possible for $1-\gamma$ given a $\gamma\in\mathbb{F}_q$ of given order $\mathcal{o}$ (where $q=p^f$).
Which is clear is that these order have the same degree (...
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Integers with exactly three factor pairs whose successors are relatively prime
I am interested in the following problem, and will appreciate pointers around how it can be solved – partially or fully – and/or indicators around whether it is even tractable:
Characterize $N \in \...
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Next smooth number
I want to find the next $n \in \mathbb{N}$ such that
$$s < n = \prod_{p_i \in \mathbb{P}_B} {p_i}^{a_i}$$
Where $\mathbb{P}_B$ is the set of primes not greater than $B$
I know that we can generate ...
3
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The kronecker symbol and factorization of $n=\frac{B^N-1}{B-1}$
Let $n=\frac{B^N-1}{B-1}$. Assume $n$ is congruent to 3 modulo 4.
We have the following:
If $N$ is 1 modulo 4, then $N$ is quadratic residue modulo $n$
and $-N$ is quadratic non-residue. The square ...
3
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answers
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Current best time for factoring in $\Bbb Q[x]$
Lenstra Lenstra Lovasz have a $O((nb)^{11})$ deterministic algorithm to factor primitive polynomials in $\Bbb Q[x]$ where $b$ is total number of bits in the polynomial and $n$ is degree of the ...
3
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counting irreducible factors
In How hard is it to compute the number of prime factors of a given integer? a question was asked on computing number of prime factors of an integer.
Suppose we have a polynomial $f(X)\in \Bbb Z[X]$ ...
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Coim factorization of a morphism in a complete well-powered category
In a complete, cocomplete and well-powered category with zero object consider the canonical factorization of a morphism $f=k\circ \mathrm{Coim}(f)$. Does cocomplete+complete+well-powered guarantee ...
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Pulling out factors in a Noetherian Domain
Let $R$ be a Noetherian domain (not-necessarily commutative), and let $S$ be a Noetherian subring of $R$. An element $r\in R$ is left $S$-irreducible if, for any $s\in S$ and $r' \in R$ with $sr'=r$, ...
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Factor group of all the sequences by the subgroup of bounded sequences
Consider the group G of the sequences of real numbers (the group operation is addition). It contains a subgroup H of bounded sequences.
Is there any nice description of the factor group G/H ?
It is ...
2
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answers
67
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Twin prime distribution centering twice a semiprime
What is the conjectured distributional behavior of semiprimes $pq$ ($p$ and $q$ are primes) having the property $2pq+1$ and $2pq-1$ are primes?
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How to decompose a matrix over a ring $F[X_1,\ldots,X_k]$ as a product of two matrices
Let $F$ be a field. Assume any reasonable conditions if needed, such as $F=\mathbb R$, $F=\mathbb C$, $F$ is a finite field, or $F$ has a specific characteristic, etc. Let $C$ be an $n\times1$ matrix ...
2
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A gsvd variation: Two SVDs with common matrix
The generalized singular value decomposition (gsvd) is described on wikipedia here. Since there are several conventions, I'll just briefly present one.
The "MATLAB" convention decomposes two ...
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What is the factorization algebra/space of an affine W algebra?
The affine vertex algebra $V_k(\mathfrak{g})$ factorizes, i.e. comes from a factorisation space, the Beilinson Drinfeld Grassmannian. Similarly, lattice vertex algebras have a factorization analogue.
...
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Factoring integers of the form $n=p q^2$ using elliptic curves
We got argument and strong experimental support
that integers of the form $n=p q^2$ can
be factored using elliptic curves easier than general integers
Q1 Is this known?
Added This is known since at ...
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Evidence of optimality of sieve algorithms
Sieve techniques apply to integer factoring and discrete logarithm to provide $2^{O(((\log n)(\log\log n)^2)^{1/3})}$ complexity for $n$ bit factoring and $n$ bit prime discrete logarithm.
The state ...
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How to prove polynomial inequality encoded from 1-factors in $K_{2n}$
Let $G=(V,E)$ be a complete graph $K_{2n}$ and it has $m$ 1-factors $f_{i,(i=1,\dots,m)}$, where $m=\frac{(2n)!}{n!2^n}$.
Some definition:
$F=\{f_{1},f_{2},...,f_{2n-1}\}$ is one 1-factorization in $...
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Heuristic for lower bounding the time for integer factorization?
I am posting this question here in hope that someone finds this heuristic useful, and maybe someone with more experience will make use of this:
As @GerryMyerson suggested here is a statement of what ...
2
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answers
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Coppersmith's method to quadrivariate degree $2$ polynomials that behave as bivariate?
We have a polynomial $f(x_1,x_2,x_3,x_4)\in\mathbb Z[x_1,x_2,x_3,x_4]$ where the only monomials are either from set $$\{x_1,x_1x_2,x_2,x_3,x_3x_4,x_4\}$$ and we seek solutions $(x_1,x_2,x_3,x_4)\in\...
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List of analytically known eigensystems?
In condensed matter physics, we often come across matrices that are multi-diagonal or banded. For example, I may have a matrix with three tridiagonal bands, or a tridiagonal band and two/four ...
2
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Factorially closed subrings
Lemma 3.2 says: Let $A$ be a UFD. Let $R \subseteq A$ be a subring of $A$ such that
$R^* = A^*$.
The following conditions are equivalent:
(i) Every irreducible element of $R$ remains irreducible in $...
2
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answers
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On reducible polynomials
Let $f(x),g(x)\in\Bbb Z[x]$ with $deg(f)>deg(g)$.
Given an integer $B$, is there any algorithm that runs in $\log^c |B|$ for some fixed $c\in \Bbb R$ to find a $h(x)\in\Bbb Z[x]$ (if one exists) ...
2
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207
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Elements of low multiplicative order and computing square roots modulo composites
In "On computing factors of cyclotomic polynomials", Richard P. Brent
gives the identity
$$ 4 \Phi_n(x) = A_n(x)^2 - (-1)^{(n-1)/2} n B_n(x)^2 \qquad (1) $$
where $n$ is odd squarefree and $A_n,B_n$ ...
1
vote
0
answers
57
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Primality testing by reversible computation using the prime number theorem
Suppose we want to build a primality testing algorithm for the numbers limited to the set $A =\{1, ..., 2^n\}$ and $n$ is reasonably large. The prime-number theorem tells us that there are ...
1
vote
0
answers
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Factorising a multivariate polynomial, in terms of products of linear polynomials, using blowups
I am considering multivariate polynomials of the form
$$f(x,y)=x^a\,y^b\,p(x,y)^c$$
(and similarly for higher dimensions). I am trying to transform these polynomials into the generic form
$$\widetilde{...
1
vote
0
answers
33
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Number of right divisors of a central skew polynomial
Let $\mathbb{F}$ be a finite field of $p$ elements, $\sigma \in \operatorname{Aut}(F)$ of order $m$, $\mathbb{F}^\sigma$ be the fixed field of $\sigma$, and $\mathbb{F}[x,\sigma]$ be a skew polynomial ...
1
vote
0
answers
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Optimal Truncation of LDL-factorization to improve conditioning
Suppose I factored real symmetric quasi-definite $ A_0= L_0 \cdot D_0 \cdot L_0^T$ and the factorization exists, with $D$ diagonal and $L$ unit lower-triangular; and suppose $L$ and $D$ are badly ...