Fix bug in checking validity of coordinate values on a chart

[egourgoulhon]

The following is a bug:

sage: M = Manifold(2, 'M')
sage: X.<x,y> = M.chart()
sage: X.add_restrictions((x^2+y^2<1, [x>0, abs(y)<1]))
sage: X.valid_coordinates(2,0)
...
AttributeError: 'list' object has no attribute 'subs'

It occurs because of some lack of depth in the analysis of the coordinate restrictions (here x<sup>2+y</sup>2<1 or (x>0 and abs(y)<1)). The current ticket fixes it by introducing a recursive function to check the coordinate restrictions.

CC: @tscrim

Component: geometry

Keywords: chart

Author: Eric Gourgoulhon

Branch/Commit: f696a38

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/22535

[egourgoulhon]

New commits:

f696a38

Fix bug in checking validity of coordinate values on a chart (#22535)

[egourgoulhon]

Commit: f696a38

[egourgoulhon]

Branch: public/manifolds/bug-coord-restrict-22535

[tscrim]

comment:2

LGTM.

[tscrim]

Reviewer: Travis Scrimshaw

[egourgoulhon]

comment:3

Thanks!

[vbraun]

Changed branch from public/manifolds/bug-coord-restrict-22535 to f696a38