Expand description
The partial order ⊑ — “permits no more than”.
This is the relation Law I is stated in, and the whole attenuation check
(US-0403) reduces to it: a flow is legal when every child’s grant is ⊑ its
parent’s. Getting it wrong makes the security guarantee wrong, so the order
is verified as a partial order — reflexive, antisymmetric, transitive — by
property tests rather than assumed.
Every comparison is three-valued. An Unknown is a refusal: the compiler
rejects rather than assume (US-0206).
Functions§
- atom_eq
- Whether two atoms denote exactly the same permission.
- atom_
leq - Whether
innerpermits no more thanouter— that is,inner ⊑ outer. - set_eq
- Whether two grant sets permit exactly the same thing.
- set_leq
- Whether
inner ⊑ outerfor grant sets. - set_lt
- Whether
inner ⊑ outerand the two are not equal — a strict narrowing.