Opened 5 years ago

Last modified 5 years ago

## #17620 new defect

# broken is_isomorphic between matrix group and permutation group

Reported by: | ncohen | Owned by: | |
---|---|---|---|

Priority: | major | Milestone: | sage-6.5 |

Component: | group theory | Keywords: | |

Cc: | vbraun | Merged in: | |

Authors: | Reviewers: | ||

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

Branch: | Commit: | ||

Dependencies: | Stopgaps: |

### Description (last modified by )

This does not work:

sage: g1 = groups.permutation.PGL(2,2) sage: g2 = groups.matrix.GO(3,2) sage: g2.is_isomorphic(g1) ... AttributeError: 'PGL_with_category' object has no attribute 'gap'

A simple hack seems to work

sage: g1.gap = g1._gap_ sage: g2.is_isomorphic(g1) True

Though I was not able to find where `_gap_`

was defined on permutation groups.

Note that `g1.is_isomorphic(g2)`

fails for another reason

sage: g1.is_isomorphic(g2) ... TypeError: right must be a permutation group

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