Short Description on Kahn’s Process Underlying Computation Model for S-net

1. Short Description on Kahn’s Process Underlying Computation Model for S-net

2. Kahn’s Computation Model • Nodes enqueue items on the output channels • Read from an input channel (block) • Node performs a deterministic computation • Conceptually unbounded buffer

3. Example integer channel X, Y, Z, T1, T2; Process f(integer in U, V; integer out W); Begin integer I; Logical B = true; Repeat Begin I := if B then wait(U) else wait(V); print(I); send I on W; B = neg(B) End; End;

4. Example Contd. Process g(integer in U; integer out V, W); Begin integer I; Logical B = true; Repeat Begin I := wait(U); if B then send I on V else send I on W; B = neg(B) End; End;

5. Example Contd. Process h(integer in U; integer INIT); Begin integer I; send INIT on V; Repeat Begin I := wait(U); send I on V; End; End; f(Y, Z, X) par g(X, T1, T2) par h(T1, Y, 0) par h(T2, Z, 1);

6. Example Contd. • Underlying theory of computation • A set of Turing machines connected via one- way tapes Z Y f h0 h1 X g T1 T2

7. Switch to S-net