let x, y be object ; :: thesis: for E being non empty set
for u, v 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
len u >= len v

let E be non empty set ; :: thesis: for u, v 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
len u >= len v

let u, v be Element of E ^omega ; :: thesis: 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
len u >= len v

let F be Subset of (E ^omega); :: thesis: for TS being non empty transition-system over F st [[x,u],[y,v]] in ==>.-relation TS holds
len u >= len v

let TS be non empty transition-system over F; :: thesis: ( [[x,u],[y,v]] in ==>.-relation TS implies len u >= len v )
assume [[x,u],[y,v]] in ==>.-relation TS ; :: thesis: len u >= len v
then x,u ==>. y,v,TS by Def4;
hence len u >= len v by Th26; :: thesis: verum