Exercise $1$:

A directory has a name and permissions to read, execute, and write.

$1.$ Propose a class model of this directory.

A file has a name and permissions to read, execute, and write.

$2.$ Propose a class model of this file.

$3.$ Make these two concepts coexist on the same diagram by proposing a generalization.

A directory can contain directories and files.

$4.$ Propose a modeling of these relationships.

Files and directories have a method for erasing and renaming. A directory also has a method for accessing the parent directory, a method for listing its content and a method for accessing one of its subdirectories by specifying its name.

$5.$ Complete your class diagram with the necessary access methods.