--  VENDING MACHINE -translation from LIVE FTS 
 C1 = pay(may).C2 + free(may).C3
 C2 = change.C3
 C3 = cancel(may).C4 + soda(may).C5 + tea(may).C6
 C4 = return.C1
 C5 = serveSoda.C7
 C6 = serveTea.C7
 C7 = take(may).C1 + open(may).C8
 C8 = take.C9
 C9 = close.C1

 SYS = C1

 Constraints { LIVE }
 
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 -- 1.   AG AF {pay or free}
 --      infinitely often, either action pay or action free is exe- cuted;
 --
 -- 2.   AG [open] AF {close}
 --      it is always the case that the execution of action open is eventually 
 --      followed by that of action close;
 --
 -- 3.   AG AF {cancel or serveSoda or serveTea}
 --      infinitely often, either action cancel or action serveSoda or action 
 --      serveTea is executed;
 --
 -- 4.   not E [ {not tea} U {serveTea}]
 --      it is not possible that action serveTea is executed without being preceded 
 --      by an execution of action tea
 --
 -- 5.   [pay] AF {take or cancel}
 --      whenever action pay is executed, eventually also ei- ther action take or 
 --      action cancel is executed
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