theorem Th91: :: REWRITE3:91

for x, y being object
for E being non empty set
for u being Element of E ^omega
for F being Subset of (E ^omega)
for TS being non empty transition-system over F st not <%> E in rng (dom the Tran of TS) holds
( x,u ==>* y,u,TS iff x = y )