2
votes
4answers
203 views
On the notion of partial semigroup
A partial binary operation on a set $X$ is just a (partial) function $\varphi: X \times X \rightharpoonup X$ (I'm using \rightharpoonup for partial maps), and a partial magma is a …
1
vote
2answers
158 views
My output of a group and inverse-closed subset in MAGMA is no longer inverse-closed when entered as input to GAP.
In MAGMA, I input the following:
G:=SmallGroup(20,3);
G;
E:=[xx:xx in G];
S:=[E[6],E[7],E[13],E[20]];
S;
S[1]^2;
S[2]^2;
S[3]*S[4];
This gives the …
7
votes
2answers
222 views
Solving the Field Membership Problem using Grobner Bases
Is there an easy way to determine whether a set of elements in a field generates the whole field or only a subfield?
Specifically, I have a subfield of $k(x,y)$ described in terms …
4
votes
1answer
284 views
What is the origin of the term magma?
Wikipedia credits Bourbaki with coining it, but doesn't provide a source. Does anyone happen to know the motivation for using this term?
5
votes
3answers
822 views
Using MAGMA for Group Theory
I've just started a PhD in Group Theory and need to use the computer programme MAGMA. I wonder if anyone could help me with a couple of (probably very basic things).
I need to pr …
1
vote
3answers
264 views
Checking for invertibility of large matrices in MAGMA
If you have a number of large matrices, and you wish to determine whether each matrix has determinant zero or not, what is the most efficient way to do this in MAGMA
(it appears t …
2
votes
2answers
197 views
Working with group cosets in MAGMA
When working with group cosets in MAGMA is there a way of treating the cosets as subsets of the overlying group. Specifically I have a group $G$ and subgroups $H$ and …
1
vote
1answer
117 views
Changing the Type of a Module in MAGMA
I am currently working with irreducible $k[G]$-modules in MAGMA for finite fields $k$ and finite groups $G$. To construct these modules, I am using the commands IrreducibleModules( …
1
vote
1answer
211 views
Homomorphisms and their restrictions in MAGMA
I am trying to look at a representation (so a homomorphism) of a group G, and see what the restriction of the representation to a subgroup of G will be. Is there an easy way (or an …
4
votes
3answers
410 views
Is there a MAGMA function to calculate the absolutely irreducible components of an algebraic curve defined over the rationals?
Given a curve defined over the rationals, is it computationaly possible to find all its absolutely irreducible components?
Is there an implementation of this in the MAGMA program? …
0
votes
0answers
126 views
Magma Coercion Syntax
Any Magma experts who know what I should write below in place of "Roots(ysoln)"? I basically want the roots of a FldFunRatMElt (variable here happens to show as "$.2"). I would g …
2
votes
0answers
193 views
How to ask Magma to compute the induced morphisim on divisor group
Suppose Magma has computed homomorphism $h$ between function fields $F1 \to F2$. Then we have an induced homomorphism $h$ on the divisor group. Now my question is that if there's a …
1
vote
1answer
383 views
Does MAGMA have a function to decide if two indefinite, integral quadratic forms are isometric?
Let's say we have two $n$-dimensional lattices $(V,b)$ and $(W,b_1)$ equipped with integral bilinear forms $b$ and $b_1$ respectively. Is there an implemented function in MAGMA tha …

