Questions tagged [computer-algebra]

Using computer-aid approach to solve algebraic problems. Questions with this tag should typically include at least one other tag indicating what sort of algebraic problem is involved, such as ac.commutative-algebra or rt.representation-theory or ag.algebraic-geometry.

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1 vote
1 answer
101 views

Factorial series $j(D)=\sum_{n=1}^\infty \frac{1}{(n^D)!}$ and hypergeometric functions

For positive integer $D$, define $j(D)=\sum_{n=1}^\infty \frac{1}{(n^D)!}$. For $D \le 6$, sage finds closed form in terms of hypergeometric functions at algrebraic arguments and fails to find closed ...
2 votes
0 answers
110 views

How to find a single-variable polynomial in a zero-dimensional ideal?

Given finitely many multivariate polynomials with algebraic coefficients that generate a zero-dimensional ideal, is there an easy way to find a nonzero single-variable polynomial in this ideal? If we ...
0 votes
1 answer
39 views

relations between non-negativity of multivariate polynomials and SOS over gradient ideal

We know there is a necessary condition for the non-negativity of multivariate polynomials in the paper "Sum of Squares Decompositions of Polynomials over their Gradient Ideals with Rational ...
1 vote
0 answers
28 views

Finite right-triple convex sets in planes

Let $\mathcal{S}$ be a set of points in $\mathbb{R}^2$. We say that $\mathcal{S}$ is right-angle convex, if for any two distinct points $P,Q\in \mathcal{S}$ there always exists another point $R\in \...
-2 votes
0 answers
132 views

Elimination over $\mathbb F_p[x,y]$

Let $p$ be a prime. Consider the two independent modular equations: $$a_1x^2+b_1y^2+c_1xy\equiv d_1\bmod p$$ $$a_2x^2+b_2y^2+c_2xy\equiv d_2\bmod p$$ Is it possible to extract the common roots $(x,y)\...
65 votes
2 answers
23k views

Does there exist a complete implementation of the Risch algorithm?

Is there a generally available (commercial or not) complete implementation of the Risch algorithm for determining whether an elementary function has an elementary antiderivative? The Wikipedia article ...
0 votes
0 answers
71 views

Potential typo in "Complete Systems of Two Addition Laws for Elliptic Curves" by Bosma and Lenstra

Here is a link to the article: https://www.sciencedirect.com/science/article/pii/S0022314X85710888?ref=cra_js_challenge&fr=RR-1. Pages 237-238 give polynomial expressions $X_3^{(2)}, Y_3^{(2)}, ...
2 votes
1 answer
103 views

Efficiency of Groebner basis for constraints of the form $(a_i x_i+b_i)(a_j x_j+b_j)$

This is based on numerical experiments in sage. Let $K$ be a ring and define the ideal where each polynomial is of the form $(a_i x_i+b_i)(a_j x_j+b_j)$ for constant $a_i,b_i,a_j,b_j$. Q1 Is it true ...
1 vote
1 answer
199 views

Finding generators of symmetric cones

I have a bunch of vectors $\mathbf v_i$ in $\mathbb R^n$. I would like to consider the cone $C$ spanned by these vectors, together with all the other vectors that can be obtained by permuting the ...
7 votes
1 answer
454 views

Computing homology groups with GAP

I’m studying the homology groups of arithmetic groups such as $SL(5,\mathbb{Z})$. I saw in the answer to this post that we can use GAP to compute some of the homology groups for $SL(3,\mathbb{Z})$. Is ...
-5 votes
1 answer
69 views

Application of Resultant in Computer Algebra [closed]

Can you guys give me some application of resultant in Computer Algebra, it will be amazing if you guys can give me some paper or book to read more. Thanks so much
12 votes
1 answer
412 views

Tarski-Seidenberg for strict inequalities and bounded quantification

This theorem says that quantifiers over real variables can be eliminated from classical first order formulae built from equations and inequalities between polynomials with rational coefficients, ie in ...
149 votes
38 answers
38k views

Computer algebra errors

In the course of doing mathematics, I make extensive use of computer-based calculations. There's one CAS that I use mostly, even though I occasionally come across out-and-out wrong answers. After ...
5 votes
0 answers
129 views

Macaulay2 seems to have divergent behavior on rings with differently ordered variables

I noticed the following strange behavior which I cannot explain. I wanted to compute the integral closure of the following ring, $$ A = \mathbb{F}_5[x,t]/(t^2 (1 - x^4) - x^5) $$ Call the integral ...
7 votes
1 answer
254 views

How to construct such a real algebraic curve

Suppose $L$ is a real line in $\mathbb{RP}^2$, my question is: for a given postive integer $n$, is it possible to find a real projective algebraic curve $C$ of degree $n$ with maximum connected ...
1 vote
3 answers
501 views

Finding maximum value of degree-3 homogeneous polynomials when variables sum to 1

I would like to be able to find maximum values of degree-3 homogeneous polynomials, when the variables are non-negative real numbers that sum to 1. For example, For example, the maximum value of $xy^...
5 votes
2 answers
327 views

Reliability of ILP approach to number-theoretic optimization

This question is inspired by the recent answer, where @RobPratt proposed to use integer linear programming (ILP) for solving a number-theoretic optimization problem. I will consider a very similar ...
1 vote
0 answers
70 views

Hall-Littlewood polynomials with sage

I need to make some computations with Sage involving Hall-Littlewood polynomials. I couldn't find any satisfying information in the Sage manuals/tutorials that I found on the internet. What I found is ...
2 votes
1 answer
249 views

Irreducibility of an explicit complex projective variety

Let $Y\subset \mathbb P^n_\mathbb C$ be a subvariety defined by a series of homogeneous polynomials $f_1, \ldots, f_t$. Is there an effective way to determine the irreducibility of $Y$ as an algebraic ...
3 votes
0 answers
87 views

Isomorphism and counting for tree quivers

Let $Q$ be a quiver which is a connected tree and let $A=KQ/I$ be a quiver algebra with $I$ an admissible ideal, meaning that $I$ is generated by paths of length $\geq 2$. Let $n$ be the number of ...
3 votes
1 answer
284 views

The associated graded algebra of a finite dimensional algebra

$\DeclareMathOperator\rad{rad}$Let $A$ be a finite dimensional algebra (we can assume that $A \cong KQ/I$, for a quiver $Q$ and an admissible ideal $I$ if that helps). Denote by $A_G$ the associated ...
7 votes
0 answers
97 views

Optimizing computations with nilpotents in a group algebra

Of course, I have a very concrete problem at hand, which has been vexing me for about a year now. But let me start with a question that has a better chance of having been answered. Let $G$ be a ...
4 votes
1 answer
328 views

GCD in $\mathbb{F}_3[T]$ with powers of linear polynomials

This is a continuation of my previous question on $\gcd$s of polynomials of type $f^n - f$. Let us call $n > 1$ simple at a prime $p$ when $p-1 \mid n-1$ but $p^k - 1 \not\mid n-1$ for all $k > ...
6 votes
2 answers
131 views

Is every parametric function family, expressed as an elemetary function, a solution to an ODE with elementary functions?

When given an ODE of the form $F(x, y, y', \ldots, y^{(n)}) = 0$, where $F$ is an elementary function, chances are that it has no solution of the form $y = G(x, c_1, \ldots, c_n)$, where $G$ is also ...
8 votes
3 answers
2k views

Rational exponential expressions

Consider the following extension of polynomials. The rational exponential expressions (REXes) are given by: The leaves 1 and $x$ for $x$ drawn from a class of variables; and Closed under the binary ...
2 votes
0 answers
157 views

Help with Macaulay2 computation of invariant ring

Consider the algebraic group $G:=\operatorname{SL}_{2}\times\operatorname{SL}_{2}$ acting on $V:=\operatorname{Mat}_{2\times 2}\oplus\operatorname{Mat}_{2\times 2}$ via the action $(A,B)\,\cdot\,(X,Y)=...
4 votes
2 answers
296 views

Algorithm for computing rational points if the rank of Jacobian is 0

Is there a general algorithm that can compute in finite time all rational points on any curve of genus $g\geq 2$ whose Jacobian has rank $0$? If not, for what special cases such algorithm is known? ...
9 votes
0 answers
285 views

Computer algebra tools for finding real dimension of an algebraic variety

I have a system of polynomial equations with the unknowns being real numbers. The set of solutions is infinite. What software can I use to compute the real dimension of the solution set? The CAD-based ...
4 votes
0 answers
94 views

Koszul algebras among finite dimensional commutative algebras

Given a local commutative artinian algebra $A$ of the form $K[x_1,...,x_n]/I$ with quadratic ideal $I$ and $K$ a field. Question 1: Is there a computer algebra system that can check whether such an ...
2 votes
0 answers
75 views

Gröbner implicitization with relationships between the variables

I have the following parametric equations, where cost$=\cos t$, cos2t$=\cos 2t$, and $A^2+B^2=1$: ...
3 votes
2 answers
187 views

What can be said about the cube-free part of $x^3 -3xy^2 +y^3$?

For $x$ and $y$ in $\mathbf{Z}$, not both zero, let $cfp(x,y)$ be the cube-free part of $x^3 -3xy^2 + y^3$ (normalized to be $> 0$). One sees: (#) $cfp(x,y)$ is either a product of primes $p$, with ...
8 votes
1 answer
1k views

Software for computing multi-graded Hilbert series

The ring of invariants $S^T$ of $k[a,b,c,d]$ under the algebraic torus action $T = k^{*}$ with weights $(1,1,-1,-1)$ is $S = k[ac,ad,bc,bd]$ which has multigraded Hilbert series $$ \frac{1 - abcd}{(1-...
5 votes
0 answers
97 views

Size of minimal generating set of ideal over Laurent polynomial ring

Recently in attacking a problem in algebraic topology relating to the construction of stably-free non-free modules over integral group rings I’ve noticed that it is often fairly easy to reduce to ...
6 votes
2 answers
340 views

Checking for a normal p-complement with a computer

Let $G$ be a finite group. Question 1: What are the fastest available programs to test whether $G$ has a normal $p$-complement (see https://en.wikipedia.org/wiki/Normal_p-complement for a definition)?...
26 votes
5 answers
6k views

Minimal polynomial of cos(π/n)

I know that $\cos(\pi/n)$ is a root of the Chebyshev polynomial $(T_n + 1)$, in fact it is the largest root of that polynomial, but often that polynomial factors. For example, if $n = 2 k$ then $\cos(\...
129 votes
74 answers
20k views

Most helpful math resources on the web

What are really helpful math resources out there on the web? Please don't only post a link but a short description of what it does and why it is helpful. Please only one resource per answer and let ...
4 votes
0 answers
188 views

Is it possible to compute Lie bialgebra structures with SageMath?

Is it possible to use SageMath (or some Linux open source program) to compute the bialgebra structures on a given finite dimensional Lie algebra? I wonder if such program can compute all the ...
9 votes
2 answers
663 views

Finite subgroups of $\mathrm{SO}(n)$ and $\mathrm{O}(n)$

Question 1:Is there a reference that lists all possible finite subgroups and their orders of $\mathrm{SO}(n)$ and $\mathrm{O}(n)$ for $n=4$ or even higher $n$ over the real numbers? I can only find ...
24 votes
5 answers
11k views

Fastest algorithm to compute the sum of primes?

Can anyone help me with references to the current fastest algorithms for counting the exact sum of primes less than some number n? I'm specifically curious about the best case running times, of ...
10 votes
2 answers
206 views

Degree 8 multilinear operations on Jordan algebras

I am interested in the dimension, or, even better, in the $S_8$-module structure of the space of degree 8 multilinear operations on Jordan algebras. Recall that a Jordan algebra is a commutative but ...
3 votes
1 answer
272 views

Siegel modular forms in Mathematica

Is there a convenient way to work with Siegel modular forms in Mathematica? I am interested in doing analytic computations using the $\chi_{10}(\Omega)$ Siegel modular form, where $\Omega$ is the $2\...
7 votes
2 answers
569 views

Deriving consequences of identities

Suppose we are given a variety in the universal algebra sense. For concreteness, suppose that we have two binary operations $+,\cdot$, three unary operations $-,\ast,'$, and two zeroary operations $0,...
5 votes
0 answers
78 views

Compute the principal polarization on $J_0(N)$ in terms of modular symbols

If we consider the modular curve $X = X_0(N)$ as a curve over $\mathbb C$ then one can describe the jacobian $J(X)$ as $H^0(X,\Omega^1_X)^\vee/H_1(X,\mathbb Z)$ as one can do for any curve $X$. ...
1 vote
2 answers
250 views

Method to solve system of exponential sums of the form $a^x+b^x=c$ given more equations than variables [closed]

Cross post with mse For example, let's say I have the following equations. \begin{gather*} a^{x-1}+b^{x-1}=337 \\ a^{x}+b^{x}=1267 \\ a^{x+1}+b^{x+1}=4825 \\ a^{x+2}+b^{x+2}=18751. \end{gather*} What ...
3 votes
0 answers
97 views

Checking the generic rank of a matrix

Suppose that $A,B\in M_{p,q}(\mathbb{Z})$ are two rectangular integer matrices of the same size. Suppose that one has a conjecture stating that the rank of the matrix $A+tB$ for Zariski generic values ...
0 votes
1 answer
142 views

Grobner basis of a submodule of a free module over polynomial ring

Let $A=\mathbb{Q} [x_1,\dots,x_n]$ be the ring of polynomials with rational coefficients. Let $T$ be an $m\times n$ matrix with entries from $A$. Consider it as a morphism of $A$-modules $T\colon A^n\...
7 votes
1 answer
349 views

About the complexity of some operation involving integers

There are two integers: $A, B$. Given the below four allowed operations (and only them): $A+1$, $A-1$, $\sqrt{A}$, $A^2$ Also, it is only allowed to take the square root of $A$ when this square root ...
0 votes
1 answer
115 views

Software to compute generators of a module over polynomial ring

Let $A=\mathbb{R}[x_1,\dots,x_n]$ be the algebra of real polynomials in $n$ variables. Fix polynomials $p_1,\dots,p_k\in A$. Consider the subset $$M:=\{(q_1,\dots,q_k)\in A^k|\, p_1q_1+\dots+p_kq_k=0\}...
4 votes
0 answers
127 views

7D simple Lie algebras over $\mathbb{F}_3$

Up to isomorphism, what are all the seven-dimensional simple Lie algebras over the field with three elements?
17 votes
4 answers
2k views

An experiment on random matrices

A bit unsure if my use/mention of proprietary software might be inappropriate or even frowned upon here. If this is the case, or if this kind of experimental question is not welcome, please let me ...

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