theorem Th86: :: REWRITE3:86

for x, y being object
for E being non empty set
for u, v, w being Element of E ^omega
for F being Subset of (E ^omega)
for TS being non empty transition-system over F st x,u ==>* y,v,TS holds
x,u ^ w ==>* y,v ^ w,TS by Th71;