let X be set ; :: thesis: for E being non empty set
for w, v being Element of E ^omega
for TS being non empty transition-system of (Lex E) \/ {(<%> E)} holds (w ^ v) -succ_of X,TS = v -succ_of (w -succ_of X,TS),TS

let E be non empty set ; :: thesis: for w, v being Element of E ^omega
for TS being non empty transition-system of (Lex E) \/ {(<%> E)} holds (w ^ v) -succ_of X,TS = v -succ_of (w -succ_of X,TS),TS

let w, v be Element of E ^omega ; :: thesis: for TS being non empty transition-system of (Lex E) \/ {(<%> E)} holds (w ^ v) -succ_of X,TS = v -succ_of (w -succ_of X,TS),TS
let TS be non empty transition-system of (Lex E) \/ {(<%> E)}; :: thesis: (w ^ v) -succ_of X,TS = v -succ_of (w -succ_of X,TS),TS
A1: now
let x be set ; :: thesis: ( x in v -succ_of (w -succ_of X,TS),TS implies x in (w ^ v) -succ_of X,TS )
assume A2: x in v -succ_of (w -succ_of X,TS),TS ; :: thesis: x in (w ^ v) -succ_of X,TS
then reconsider r = x as Element of TS ;
consider p being Element of TS such that
A3: p in w -succ_of X,TS and
A4: p,v ==>* r,TS by A2, REWRITE3:103;
consider q being Element of TS such that
A5: q in X and
A6: q,w ==>* p,TS by A3, REWRITE3:103;
q,w ^ v ==>* r,TS by A4, A6, REWRITE3:99;
hence x in (w ^ v) -succ_of X,TS by A5, REWRITE3:103; :: thesis: verum
end;
now
let x be set ; :: thesis: ( x in (w ^ v) -succ_of X,TS implies x in v -succ_of (w -succ_of X,TS),TS )
assume A7: x in (w ^ v) -succ_of X,TS ; :: thesis: x in v -succ_of (w -succ_of X,TS),TS
then reconsider r = x as Element of TS ;
consider q being Element of TS such that
A8: q in X and
A9: q,w ^ v ==>* r,TS by A7, REWRITE3:103;
consider p being Element of TS such that
A10: q,w ==>* p,TS and
A11: p,v ==>* r,TS by A9, Th29;
p in w -succ_of X,TS by A8, A10, REWRITE3:103;
hence x in v -succ_of (w -succ_of X,TS),TS by A11, REWRITE3:103; :: thesis: verum
end;
hence (w ^ v) -succ_of X,TS = v -succ_of (w -succ_of X,TS),TS by A1, TARSKI:2; :: thesis: verum