/usr/include/mrpt/nav/ is in libmrpt-dev 1:1.3.2-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mrpt/nav/include/
/usr/include/mrpt/nav/include/mrpt/
/usr/include/mrpt/nav/include/mrpt/nav/
/usr/include/mrpt/nav/include/mrpt/nav.h
/usr/include/mrpt/nav/include/mrpt/nav/holonomic/
/usr/include/mrpt/nav/include/mrpt/nav/holonomic/CAbstractHolonomicReactiveMethod.h
/usr/include/mrpt/nav/include/mrpt/nav/holonomic/CHolonomicLogFileRecord.h
/usr/include/mrpt/nav/include/mrpt/nav/holonomic/CHolonomicND.h
/usr/include/mrpt/nav/include/mrpt/nav/holonomic/CHolonomicVFF.h
/usr/include/mrpt/nav/include/mrpt/nav/link_pragmas.h
/usr/include/mrpt/nav/include/mrpt/nav/planners/
/usr/include/mrpt/nav/include/mrpt/nav/planners/PlannerRRT_SE2_TPS.h
/usr/include/mrpt/nav/include/mrpt/nav/planners/PlannerSimple2D.h
/usr/include/mrpt/nav/include/mrpt/nav/planners/TMoveTree.h
/usr/include/mrpt/nav/include/mrpt/nav/reactive/
/usr/include/mrpt/nav/include/mrpt/nav/reactive/CAbstractPTGBasedReactive.h
/usr/include/mrpt/nav/include/mrpt/nav/reactive/CAbstractReactiveNavigationSystem.h
/usr/include/mrpt/nav/include/mrpt/nav/reactive/CLogFileRecord.h
/usr/include/mrpt/nav/include/mrpt/nav/reactive/CReactiveNavigationSystem.h
/usr/include/mrpt/nav/include/mrpt/nav/reactive/CReactiveNavigationSystem3D.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CPTG1.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CPTG2.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CPTG3.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CPTG4.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CPTG5.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CPTG6.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CPTG7.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/CParameterizedTrajectoryGenerator.h
/usr/include/mrpt/nav/include/mrpt/nav/tpspace/motion_planning_utils.h
/usr/include/mrpt/nav/include/mrpt/reactivenav/
/usr/include/mrpt/nav/include/mrpt/reactivenav.h
/usr/include/mrpt/nav/include/mrpt/reactivenav/CReactiveNavigationSystem.h
/usr/include/mrpt/nav/include/mrpt/reactivenav/CReactiveNavigationSystem3D.h
/usr/include/mrpt/nav/include/mrpt/reactivenav/motion_planning_utils.h