| symbol | what it represents | 
|---|---|
| S | set of subjects | 
| O | set of objects | 
| P | set of rights | 
| r ∈ P | read right | 
| a ∈ P | write right (equivalent to append) | 
| w ∈ P | read and write right | 
| e ∈ P | empty right | 
| C | set of clearances (for subjects) or classifications (for objects) | 
| K | set of categories | 
| L = C × K | set of security levels | 
| fs(s) | maximum security level of subject s | 
| fc(s) | current security level of subject s | 
| fo(o) | security level of object o | 
| F = { fs(s), fc(s), fo(o)) } | set of functions to map entity into security level | 
| f = (fs(s), fc(s), fo(o)) | an element of the set F | 
| H | set of hierarchy functions h ∈ H, where h: O → P(O) | 
| M | set of possible access control matrices | 
| V = { (b, m, f, h) } | set of states of system | 
| b | access control matrix m that excludes rights not allowed by f | 
| R | set of requests for access | 
| D | set of outcomes | 
| y ∈ P | the access is allowed | 
| n ∈ P | the access is not allowed | 
| i ∈ P | the request is illegal | 
| e ∈ P | an error occurred in processing the request | 
| W ⊆ R × D × V × V | set of actions of the system | 
| X = RN | set of sequences of requests | 
| Y = DN | set of sequences of decisions | 
| Z = VN | set of sequences of states | 
| Σ(R, D, W, z0) ∈ X × Y × Y | system representation | 
                
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                ECS 235B, Foundations of Computer and Information Security Version of January 21, 2022 at 11:59AM 
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            You can also obtain a PDF version of this. |