oscar-system/gitfans

GIT fan algorithms

This code is obsolete, use the GITFans code in Oscar.jl instead

gitfans's Issues

Columns vs rows

The notebook talks about the "$i$-th column of the matrix $Q$ is the degree $\operatorname{deg}(T_i)\in \mathbb{Z}^5$" -- but the rows are in Z^5, not the columns? Is this a typo or am I misunderstanding something?

new Oscar features

A possibility would be to change the notebook/ implementation to use the recent Oscar features. On Oscar#master this should work

Qt, T = PolynomialRing(QQ, :T=>1:10)
D = free_abelian_group(5)
Q = [...]
w = [D(Q[i, :]) for i=1:10]
R = grade(Qt, w)
a = ideal(R, [T[5]*T[10] - T[6]*T[9] + T[7]*T[8],
T[1]*T[9] - T[2]*T[7] + T[4]*T[5],
T[1]*T[8] - T[2]*T[6] + T[3]*T[5],
T[1]*T[10] - T[3]*T[7] + T[4]*T[6],
T[2]*T[10] - T[3]*T[9] + T[4]*T[8]])

or
a = ideal([R[5] * R[10] ....])

q, mq = quo(R, a)

...
Of course, internally all serious computations in R, a, Qt, are done in Singular, but it looks neater
Also, in the notebook, now automatically, you should see T_1 with proper subscripts

It would be cool if fans, cones, ... would be proper julia structures, then some of the interfacing would be easier to read....