for x1, x2, y1, y2, z being object
for E being non empty set
for F being Subset of (E ^omega)
for TS being non empty transition-system over F st TS is deterministic & x1,x2 ==>* y1,z,TS & x1,x2 ==>* y2,z,TS holds
y1 = y2 by Th80;