@TechReport{	  it:2004-012,
  author	= {Parosh Aziz Abdulla and Johann Deneuz and Pritha Mahata},
  title		= {Multi-Clock Timed Networks},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Division of Computer Systems},
  year		= {2004},
  number	= {2004-012},
  month		= apr,
  abstract	= {We consider verification of safety properties for
		  parameterized systems of timed processes, so called {\it
		  timed networks}. A timed network consists of a finite state
		  process, called a controller, and an arbitrary set of
		  identical timed processes. In a previous work, we showed
		  that checking safety properties is decidable in the case
		  where each timed process is equipped with a single
		  real-valued clock. It was left open whether the result
		  could be extended to multi-clock timed networks. We show
		  that the problem becomes undecidable when each timed
		  process has two clocks.
		  
		  On the other hand, we show that the problem is decidable
		  when clocks range over a discrete time domain. This
		  decidability result holds when processes have any finite
		  number of clocks.}
}