urgent chan SendSR, SendRS;
chan RcvSR, RcvRS;
Sender
Wait
Send
link
TransmitRS
Wait
transmitSR
Receiver
Send
Wait
mittente=Sender();
destinatario=Receiver();
canale = link();
system mittente,destinatario,canale;
E<> destinatario.Send
(mittente.Wait && x==0) --> (destinatario.Send && x <=50)
mittente.Wait --> destinatario.Send
A[] !(deadlock)