let L be Lattice; :: thesis: for f being Function of the carrier of L, the carrier of L
for x being Element of L
for O being Ordinal holds (f,(succ O)) +. x = f . ((f,O) +. x)

let f be Function of the carrier of L, the carrier of L; :: thesis: for x being Element of L
for O being Ordinal holds (f,(succ O)) +. x = f . ((f,O) +. x)

let x be Element of L; :: thesis: for O being Ordinal holds (f,(succ O)) +. x = f . ((f,O) +. x)
let O be Ordinal; :: thesis: (f,(succ O)) +. x = f . ((f,O) +. x)
deffunc H1( Ordinal, set ) -> set = f . $2;
deffunc H2( Ordinal, Sequence) -> Element of the carrier of L = "\/" ((rng $2),L);
deffunc H3( Ordinal) -> set = (f,$1) +. x;
A1: for O being Ordinal
for y being object holds
( y = H3(O) iff ex L0 being Sequence st
( y = last L0 & dom L0 = succ O & L0 . 0 = x & ( for C being Ordinal st succ C in succ O holds
L0 . (succ C) = H1(C,L0 . C) ) & ( for C being Ordinal st C in succ O & C <> 0 & C is limit_ordinal holds
L0 . C = H2(C,L0 | C) ) ) ) by Def4;
for O being Ordinal holds H3( succ O) = H1(O,H3(O)) from ORDINAL2:sch 9(A1);
hence (f,(succ O)) +. x = f . ((f,O) +. x) ; :: thesis: verum