Dear OpenMesh maintainers, We encountered a configuration where PolyConnectivity::is_collapse_ok fails to return a correct result for a triangle mesh, while TriConnectivity::is_collapse_ok does. We attach code to reproduce the problem (openmesh_bug_is_collapse_ok.cpp). See the comments in that file for more details on the bug. Moreover, we attach a patch against OpenMesh-7.1 to fix the problem (openmesh_patch_is_collapse_ok.patch). The patch basically reproduces the logic of TriConnectivity::is_collapse_ok for this special case. Not related, but did you have time to look at this issue https://lists.rwth-aachen.de/hyperkitty/list/openmesh@lists.rwth-aachen.de/t... we reported some time ago? thanks, Simon -- Dr. Simon Flöry Rechenraum e.U. Stutterheimstraße 16-18/2/20a, 1150 Wien, Austria phone: +43 (0)1 789061269 mobile: +43 (0)681 81502316 skype: simon.floery Commercial Register No. FN 385715d (Handelsgericht Wien) This e-mail contains confidential information. If you are not the intended recipient, you must not disclose nor use the contents of this e-mail. In case you have received this e-mail in error, we ask you to inform us and delete this e-mail.