ivy/test/client_server_mc2.ivy

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#lang ivy1.7
type client
type server
relation link(X:client, Y:server)
relation semaphore(X:server)
relation
after init {
semaphore(W) := true;
link(X,Y) := false
}
action connect(x:client,y:server) = {
assume semaphore(y);
link(x,y) := true;
semaphore(y) := false
}
action disconnect(x:client,y:server) = {
assume link(x,y);
link(x,y) := false;
semaphore(y) := true
}
invariant [safety] ~(X ~= Z & link(X,Y) & link(Z,Y))
axiom __X = X & __Z = X -> __X = __Z
axiom __Y = Y -> (semaphore(__Y) = semaphore(Y))
axiom __X = X & __Y = Y -> (link(__X,__Y) = link(X,Y))
axiom __Z = X & __Y = Y -> (link(__Z,__Y) = link(X,Y))
export connect
export disconnect