diff --git a/Concurrent Systems/notes/6 - Atomicity.md b/Concurrent Systems/notes/6 - Atomicity.md index 0827fae..687889b 100644 --- a/Concurrent Systems/notes/6 - Atomicity.md +++ b/Concurrent Systems/notes/6 - Atomicity.md @@ -60,7 +60,13 @@ We now show that $\to$ is acyclic. - $op3 \to_H op4$ means that $res(op3) <_H inv(op4)$ - We would then have that $res(op1) <_H inv(op2) <_H res(op3) <_H inv(op4)$ - - So by transitivity $res(op1) <_H inv(op4)$ + - So by transitivity $res(op1) <_H inv(op4)$, i.e. $op1 \to_H op4$ + - IN CONTRADICTION WITH HAVING CHOSEN A SHORTEST CYCLE + - as if op4 = op1, then this could not happen as $\to$ is a total order. + +This said, we can say that **every DAG admits a topological order** (a total order of its nodes that respects the edges), we will call $\to'$ the topological order for $\to$ + +Let us define a linearization of $\hat{H}$ as follows: $$\hat{S}=inv(op1)res(op1)$$ > [!PDF|red] class 6, p.6> we would have a cycle of length