theorem Th77: :: REWRITE3:77

for x, y being object
for E being non empty set
for v, w being Element of E ^omega
for F being Subset of (E ^omega)
for TS being non empty transition-system over F holds
( <%> E in rng (dom the Tran of TS) or not ==>.-relation TS reduces [x,v],[y,w] or len v > len w or ( x = y & v = w ) )