theorem Th87: :: REWRITE3:87

for x1, x2, y1, y2 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 x1,x2 ==>. y1,y2,TS holds
x1,x2 ==>* y1,y2,TS by Th74;