Opened 6 years ago

Last modified 6 years ago

## #21228 new enhancement

# Polyhedron.restricted_automorphism_group(): allow returning an actual affine group

Reported by: | Matthias Köppe | Owned by: | |
---|---|---|---|

Priority: | major | Milestone: | sage-wishlist |

Component: | geometry | Keywords: | |

Cc: | Jeroen Demeyer, Volker Braun | Merged in: | |

Authors: | Reviewers: | ||

Report Upstream: | N/A | Work issues: | |

Branch: | Commit: | ||

Dependencies: | Stopgaps: |

### Description

This is a follow-up on #20259, which added the `output="matrix"`

argument to `restricted_automorphism_group`

. It returns a `MatrixGroup`

.

In this ticket, I propose to add `output="affine"`

to return an `AffineGroup`

.

### Change History (5)

### comment:1 Changed 6 years ago by

### comment:2 follow-up: 3 Changed 6 years ago by

Answering my own question: it seems that an `AffineGroup`

always refers to the group of *all* affine transformations, not a subgroup.

So, as far as I can tell, the object you want to return doesn't exist in Sage (and it would be non-trivial work to implement it).

### comment:3 Changed 6 years ago by

Milestone: | sage-7.4 → sage-wishlist |
---|

Replying to jdemeyer:

Answering my own question: it seems that an

`AffineGroup`

always refers to the group ofallaffine transformations, not a subgroup.So, as far as I can tell, the object you want to return doesn't exist in Sage (and it would be non-trivial work to implement it).

Thanks! I was already wondering why there was no method to make a subgroup (though methods `subsemigroup`

and `submonoid`

exist).

### comment:5 Changed 6 years ago by

I've instead created a ticket for subgroups of `AffineGroup`

- #21275

**Note:**See TracTickets for help on using tickets.

Replying to mkoeppe:

I wonder why I didn't do that in #20259. Either I didn't know about

`AffineGroup`

or it was lacking in functionality.