/usr/include/mrpt/hmtslam/ is in libmrpt-dev 1:1.4.0-7.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mrpt/hmtslam/include/
/usr/include/mrpt/hmtslam/include/mrpt/
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CHMHMapArc.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CHMHMapNode.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CHMTSLAM.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CHierarchicalMHMap.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CHierarchicalMapMHPartition.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CLocalMetricHypothesis.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CRobotPosesGraph.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CTopLCDetectorBase.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CTopLCDetector_FabMap.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/CTopLCDetector_GridMatching.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/HMT_SLAM_common.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/hmtslam_impexp.h
/usr/include/mrpt/hmtslam/include/mrpt/hmtslam/link_pragmas.h