/usr/include/fl/norm/ is in libfuzzylite-dev 5.1+dfsg-5.
This file is owned by root:root, with mode 0o755.
..
/usr/include/fl/norm/Norm.h
/usr/include/fl/norm/SNorm.h
/usr/include/fl/norm/TNorm.h
/usr/include/fl/norm/s/
/usr/include/fl/norm/s/AlgebraicSum.h
/usr/include/fl/norm/s/BoundedSum.h
/usr/include/fl/norm/s/DrasticSum.h
/usr/include/fl/norm/s/EinsteinSum.h
/usr/include/fl/norm/s/HamacherSum.h
/usr/include/fl/norm/s/Maximum.h
/usr/include/fl/norm/s/NilpotentMaximum.h
/usr/include/fl/norm/s/NormalizedSum.h
/usr/include/fl/norm/t/
/usr/include/fl/norm/t/AlgebraicProduct.h
/usr/include/fl/norm/t/BoundedDifference.h
/usr/include/fl/norm/t/DrasticProduct.h
/usr/include/fl/norm/t/EinsteinProduct.h
/usr/include/fl/norm/t/HamacherProduct.h
/usr/include/fl/norm/t/Minimum.h
/usr/include/fl/norm/t/NilpotentMinimum.h