U11ttNU21ttsplusNMU41ttplusxNMNandttXU31tt0isNatttisNatandisNatisNatisNatplusN0U11isNatplusNsMU21andisNatxN0U31isNatxNsMU41andisNat2.1
AProVE
30c4685dac1f9efc56544a9a1f70f53689c698fa rene 20120209 unpublished dirty
http://aprove.informatik.rwth-aachen.de/
John
Doe