theorem :: REWRITE3:39

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]] in ==>.-relation TS holds
[[x,(u ^ w)],[y,(v ^ w)]] in ==>.-relation TS