:: deftheorem Def4 defines ==>.-relation REWRITE3:def 4 :
for E being non empty set
for F being Subset of (E ^omega)
for TS being non empty transition-system over F
for b₄ being Relation of [: the carrier of TS,(E ^omega):] holds
( b₄ = ==>.-relation TS iff for x1, x2, y1, y2 being object holds
( [[x1,x2],[y1,y2]] in b₄ iff x1,x2 ==>. y1,y2,TS ) );