title Replication - Split Brain 

participant Client1 
participant Instance1
participant Instance2
participant Client2

state over Client1, Client2, Instance1, Instance2: W0
state over Client1 : W0 -> W1
Client1 -> +Instance1: Push W1
Instance1 -> -Client1: Ack W1
state over Instance1 : W0 -> W1
state over Instance1 : Crash

state over Client2 : W0 -> W2
Client2 -> +Instance2: Push W2
Instance2 -> -Client2 : Ack W2
state over Instance2 : W0 -> W2

state over Instance1:  Restart

par 
    Instance2->Instance1: Replicate W2
    Instance1->Instance2: Replicate W1 
end

parallel {
    state over Instance2: W0 -> W1 
    state over Instance1: W0 -> W2
    state over Client1: W0 -> W1
    state over Client2: W0 -> W2
}

note over Instance1, Instance2
    Instances status diverged 
    and is even swapped from 
    original 
end note