Improved undecidability results on weighted timed automata

In this paper, we strengthen two recent undecidability results about weighted timed automata, an extension of timed automata with cost variables. More precisely, we propose new encodings of a Minsky machine. that only require three clocks and one stopwatch cost, while previous reductions required five clocks and one stopwatch cost. (c) 2006 Elsevier B.V. All rights reserved.