fix variable_names_recursive for polynomial rings over quotient rings

saliola commented 5 years ago

variable_names_recursive is suppose to return the list of variable names of a polynomial ring and its base rings, as if it were a single multi-variate polynomial ring.

It works if the base ring is a polynomial ring:

sage: R = PolynomialRing(GF(5), "x,y")
sage: PolynomialRing(R, 'q, t').variable_names_recursive()
('x', 'y', 'q', 't')

but not if the base ring is a quotient of a polynomial ring:

sage: x, y = R.gens()
sage: Q = R.quotient([x^2 - y^3])
sage: PolynomialRing(Q, 'q,t').variable_names_recursive() # should be ('xbar', 'ybar', 'q', 't')
('q', 't')

CC: @mwageringel

Component: commutative algebra

Keywords: IMA Coding Sprint

Issue created by migration from https://trac.sagemath.org/ticket/28580

embray commented 4 years ago

comment:1

Ticket retargeted after milestone closed

mkoeppe commented 4 years ago

comment:2

Moving tickets to milestone sage-9.2 based on a review of last modification date, branch status, and severity.

mkoeppe commented 3 years ago

comment:4

Moving to 9.4, as 9.3 has been released.

sagemath / sage

fix variable_names_recursive for polynomial rings over quotient rings #28580