/usr/include/regina-normal/triangulation/ is in regina-normal-dev 4.96-2.1build2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/regina-normal/triangulation/dimtraits.h
/usr/include/regina-normal/triangulation/nboundarycomponent.h
/usr/include/regina-normal/triangulation/ncomponent.h
/usr/include/regina-normal/triangulation/nedge.h
/usr/include/regina-normal/triangulation/nexampletriangulation.h
/usr/include/regina-normal/triangulation/nface.h
/usr/include/regina-normal/triangulation/nfacepair.h
/usr/include/regina-normal/triangulation/nfacetspec.h
/usr/include/regina-normal/triangulation/ngenericisomorphism.h
/usr/include/regina-normal/triangulation/ngenericisomorphism.tcc
/usr/include/regina-normal/triangulation/nhomologicaldata.h
/usr/include/regina-normal/triangulation/nisomorphism.h
/usr/include/regina-normal/triangulation/nperm.h
/usr/include/regina-normal/triangulation/npermit.h
/usr/include/regina-normal/triangulation/ntetface.h
/usr/include/regina-normal/triangulation/ntetrahedron.h
/usr/include/regina-normal/triangulation/ntriangle.h
/usr/include/regina-normal/triangulation/ntriangulation.h
/usr/include/regina-normal/triangulation/nvertex.h
/usr/include/regina-normal/triangulation/nxmltrireader.h