In the "docs-style-sharing" example, what is the reason for the

usergroup#manager

in the 4 clauses, shouldn't the

usergroup#member

include the former set?

definition user {}

definition resource {
    relation manager: user | usergroup#member | usergroup#manager
    relation viewer: user | usergroup#member | usergroup#manager

    permission manage = manager
    permission view = viewer + manager
}

definition usergroup {
    relation manager: user | usergroup#member | usergroup#manager
    relation direct_member: user | usergroup#member | usergroup#manager

    permission member = direct_member + manager
}

...

Such that it could be simplified to

definition user {}

definition resource {
    relation manager: user | usergroup#member
    relation viewer: user | usergroup#member

    permission manage = manager
    permission view = viewer + manager
}

definition usergroup {
    relation manager: user | usergroup#member
    relation direct_member: user | usergroup#member

    permission member = direct_member + manager
}

...