Interactors: Formal Architectural Models of User Interface Software

ion-side and Display-side behaviours. Interactors can be ‘observed’ from the abstraction or the display sides. The abstraction-side behaviour of the interactor is observed by interaction at gates Notation Meaning r q n   →  μ μ .. 1 r q q q q q q n n n →  → → →  →  ∃ − μ μ μ 1 2 1 1 ... | ... 2 1 r q ε ⇒ r q n r q n →  ≥ ∃ ∨ ≡ τ | 1 r q μ ⇒ r q q q q q ε μ ε ⇒ →  ⇒ ∃ 2 1 2 1 | , r q n μ μ .. 1 ⇒ r q q q q q n n n n μ μ μ μ ⇒ ⇒ ⇒ ⇒ ∃ − − − 1 1 1 1 1 2 1 ... | .. n q μ μ .. 1 ⇒/ r q r n μ μ .. 1 | ⇒ ∃/ Tr(q) } | { r q r A σ σ ⇒ • ∃ ∈ ∗ Table 1. Some notation to describe traces of processes. Traces are sequences of observable actions in a set A that describe transitions from the initial state q of a process to some other state r. Internal (non-observable) actions are denoted as τ.