for G being Graph
for c being Chain of G
for vs being FinSequence of the carrier of G
for e being set st e in the carrier' of G & vs is_vertex_seq_of c & vs . (len vs) = the Source of G . e holds
( c ^ <*e*> is Chain of G & ex vs9 being FinSequence of the carrier of G st
( vs9 = vs ^' <*( the Source of G . e),( the Target of G . e)*> & vs9 is_vertex_seq_of c ^ <*e*> & vs9 . 1 = vs . 1 & vs9 . (len vs9) = the Target of G . e ) )