# Boolean operator gmsh

**URL:** <https://fenicsproject.discourse.group/t/boolean-operator-gmsh/9843>\
**Category:** mesh\
**Created:** [November 26, 2022, 4:22am UTC](https://fenicsproject.discourse.group/t/boolean-operator-gmsh/9843 "2022-11-26T04:22:46Z")\
**Posts on this page:** 1\
**Showing post:** 15

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**Author:** ![dokken](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/dokken/32/1560_2.png) [@dokken](https://fenicsproject.discourse.group/u/dokken)\
**Post date:** [March 8, 2023, 3:03pm UTC](https://fenicsproject.discourse.group/t/boolean-operator-gmsh/9843/15 "2023-03-08T15:03:20Z")

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So, as the error says, the mesh of quadrilateral elements that you have created cannot be ordered in a consistent way (this issue is related to: [Unable to order quadrilateral cell](https://fenicsproject.discourse.group/t/unable-to-order-quadrilateral-cell/1396))  
which lead to the paper by @mscroggs : [https://dl.acm.org/doi/full/10.1145/3524456](https://dl.acm.org/doi/full/10.1145/3524456) (arxiv version: [[2102.11901] Construction of arbitrary order finite element degree-of-freedom maps on polygonal and polyhedral cell meshes](https://arxiv.org/abs/2102.11901)) which has been implemented in DOLFINx.

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