let A be non empty set ; :: thesis: for L being lower-bounded LATTICE
for d being BiFunction of A,L st d is symmetric holds
for q being QuadrSeq of d
for O being Ordinal holds ConsecutiveDelta2 q,O is symmetric

let L be lower-bounded LATTICE; :: thesis: for d being BiFunction of A,L st d is symmetric holds
for q being QuadrSeq of d
for O being Ordinal holds ConsecutiveDelta2 q,O is symmetric

let d be BiFunction of A,L; :: thesis: ( d is symmetric implies for q being QuadrSeq of d
for O being Ordinal holds ConsecutiveDelta2 q,O is symmetric )

assume A1: d is symmetric ; :: thesis: for q being QuadrSeq of d
for O being Ordinal holds ConsecutiveDelta2 q,O is symmetric

let q be QuadrSeq of d; :: thesis: for O being Ordinal holds ConsecutiveDelta2 q,O is symmetric
let O be Ordinal; :: thesis: ConsecutiveDelta2 q,O is symmetric
defpred S1[ Ordinal] means ConsecutiveDelta2 q,$1 is symmetric ;
A2: S1[ {} ]
proof
let x, y be Element of ConsecutiveSet2 A,{} ; :: according to LATTICE5:def 6 :: thesis: (ConsecutiveDelta2 q,{} ) . x,y = (ConsecutiveDelta2 q,{} ) . y,x
reconsider x' = x, y' = y as Element of A by Th15;
thus (ConsecutiveDelta2 q,{} ) . x,y = d . x',y' by Th19
.= d . y',x' by A1, LATTICE5:def 6
.= (ConsecutiveDelta2 q,{} ) . y,x by Th19 ; :: thesis: verum
end;
A3: for O1 being Ordinal st S1[O1] holds
S1[ succ O1]
proof
let O1 be Ordinal; :: thesis: ( S1[O1] implies S1[ succ O1] )
assume ConsecutiveDelta2 q,O1 is symmetric ; :: thesis: S1[ succ O1]
then A4: new_bi_fun2 (ConsecutiveDelta2 q,O1),(Quadr2 q,O1) is symmetric by Th11;
let x, y be Element of ConsecutiveSet2 A,(succ O1); :: according to LATTICE5:def 6 :: thesis: (ConsecutiveDelta2 q,(succ O1)) . x,y = (ConsecutiveDelta2 q,(succ O1)) . y,x
reconsider x' = x, y' = y as Element of new_set2 (ConsecutiveSet2 A,O1) by Th16;
A5: ConsecutiveDelta2 q,(succ O1) = new_bi_fun2 (BiFun (ConsecutiveDelta2 q,O1),(ConsecutiveSet2 A,O1),L),(Quadr2 q,O1) by Th20
.= new_bi_fun2 (ConsecutiveDelta2 q,O1),(Quadr2 q,O1) by LATTICE5:def 16 ;
hence (ConsecutiveDelta2 q,(succ O1)) . x,y = (new_bi_fun2 (ConsecutiveDelta2 q,O1),(Quadr2 q,O1)) . y',x' by A4, LATTICE5:def 6
.= (ConsecutiveDelta2 q,(succ O1)) . y,x by A5 ;
:: thesis: verum
end;
A6: for O1 being Ordinal st O1 <> {} & O1 is limit_ordinal & ( for O2 being Ordinal st O2 in O1 holds
S1[O2] ) holds
S1[O1]
proof
let O2 be Ordinal; :: thesis: ( O2 <> {} & O2 is limit_ordinal & ( for O2 being Ordinal st O2 in O2 holds
S1[O2] ) implies S1[O2] )

assume A7: ( O2 <> {} & O2 is limit_ordinal & ( for O1 being Ordinal st O1 in O2 holds
ConsecutiveDelta2 q,O1 is symmetric ) ) ; :: thesis: S1[O2]
deffunc H1( Ordinal) -> BiFunction of (ConsecutiveSet2 A,$1),L = ConsecutiveDelta2 q,$1;
consider Ls being T-Sequence such that
A8: ( dom Ls = O2 & ( for O1 being Ordinal st O1 in O2 holds
Ls . O1 = H1(O1) ) ) from ORDINAL2:sch 2();
A9: ConsecutiveDelta2 q,O2 = union (rng Ls) by A7, A8, Th21;
deffunc H2( Ordinal) -> set = ConsecutiveSet2 A,$1;
consider Ts being T-Sequence such that
A10: ( dom Ts = O2 & ( for O1 being Ordinal st O1 in O2 holds
Ts . O1 = H2(O1) ) ) from ORDINAL2:sch 2();
A11: ConsecutiveSet2 A,O2 = union (rng Ts) by A7, A10, Th17;
set CS = ConsecutiveSet2 A,O2;
reconsider f = union (rng Ls) as BiFunction of (ConsecutiveSet2 A,O2),L by A9;
f is symmetric
proof
let x, y be Element of ConsecutiveSet2 A,O2; :: according to LATTICE5:def 6 :: thesis: f . x,y = f . y,x
consider x1 being set such that
A12: ( x in x1 & x1 in rng Ts ) by A11, TARSKI:def 4;
consider o1 being set such that
A13: ( o1 in dom Ts & x1 = Ts . o1 ) by A12, FUNCT_1:def 5;
consider y1 being set such that
A14: ( y in y1 & y1 in rng Ts ) by A11, TARSKI:def 4;
consider o2 being set such that
A15: ( o2 in dom Ts & y1 = Ts . o2 ) by A14, FUNCT_1:def 5;
reconsider o1 = o1, o2 = o2 as Ordinal by A13, A15;
A16: x in ConsecutiveSet2 A,o1 by A10, A12, A13;
A17: y in ConsecutiveSet2 A,o2 by A10, A14, A15;
A18: Ls . o1 = ConsecutiveDelta2 q,o1 by A8, A10, A13;
then reconsider h1 = Ls . o1 as BiFunction of (ConsecutiveSet2 A,o1),L ;
A19: h1 is symmetric
proof
let x, y be Element of ConsecutiveSet2 A,o1; :: according to LATTICE5:def 6 :: thesis: h1 . x,y = h1 . y,x
A20: ConsecutiveDelta2 q,o1 is symmetric by A7, A10, A13;
thus h1 . x,y = (ConsecutiveDelta2 q,o1) . x,y by A8, A10, A13
.= (ConsecutiveDelta2 q,o1) . y,x by A20, LATTICE5:def 6
.= h1 . y,x by A8, A10, A13 ; :: thesis: verum
end;
A21: dom h1 = [:(ConsecutiveSet2 A,o1),(ConsecutiveSet2 A,o1):] by FUNCT_2:def 1;
A22: Ls . o2 = ConsecutiveDelta2 q,o2 by A8, A10, A15;
then reconsider h2 = Ls . o2 as BiFunction of (ConsecutiveSet2 A,o2),L ;
A23: h2 is symmetric
proof
let x, y be Element of ConsecutiveSet2 A,o2; :: according to LATTICE5:def 6 :: thesis: h2 . x,y = h2 . y,x
A24: ConsecutiveDelta2 q,o2 is symmetric by A7, A10, A15;
thus h2 . x,y = (ConsecutiveDelta2 q,o2) . x,y by A8, A10, A15
.= (ConsecutiveDelta2 q,o2) . y,x by A24, LATTICE5:def 6
.= h2 . y,x by A8, A10, A15 ; :: thesis: verum
end;
A25: dom h2 = [:(ConsecutiveSet2 A,o2),(ConsecutiveSet2 A,o2):] by FUNCT_2:def 1;
per cases ( o1 c= o2 or o2 c= o1 ) ;
suppose o1 c= o2 ; :: thesis: f . x,y = f . y,x
then A26: ConsecutiveSet2 A,o1 c= ConsecutiveSet2 A,o2 by Th22;
then reconsider x' = x, y' = y as Element of ConsecutiveSet2 A,o2 by A10, A14, A15, A16;
ConsecutiveDelta2 q,o2 in rng Ls by A8, A10, A15, A22, FUNCT_1:def 5;
then A27: h2 c= f by A22, ZFMISC_1:92;
A28: ( [x,y] in dom h2 & [y,x] in dom h2 ) by A16, A17, A25, A26, ZFMISC_1:106;
hence f . x,y = h2 . x',y' by A27, GRFUNC_1:8
.= h2 . y',x' by A23, LATTICE5:def 6
.= f . y,x by A27, A28, GRFUNC_1:8 ;
:: thesis: verum
end;
suppose o2 c= o1 ; :: thesis: f . x,y = f . y,x
then A29: ConsecutiveSet2 A,o2 c= ConsecutiveSet2 A,o1 by Th22;
then reconsider x' = x, y' = y as Element of ConsecutiveSet2 A,o1 by A10, A12, A13, A17;
ConsecutiveDelta2 q,o1 in rng Ls by A8, A10, A13, A18, FUNCT_1:def 5;
then A30: h1 c= f by A18, ZFMISC_1:92;
A31: ( [x,y] in dom h1 & [y,x] in dom h1 ) by A16, A17, A21, A29, ZFMISC_1:106;
hence f . x,y = h1 . x',y' by A30, GRFUNC_1:8
.= h1 . y',x' by A19, LATTICE5:def 6
.= f . y,x by A30, A31, GRFUNC_1:8 ;
:: thesis: verum
end;
end;
end;
hence S1[O2] by A7, A8, Th21; :: thesis: verum
end;
for O being Ordinal holds S1[O] from ORDINAL2:sch 1(A2, A3, A6);
hence ConsecutiveDelta2 q,O is symmetric ; :: thesis: verum