let A1, A2 be non empty set ; :: thesis: for B1, B2 being set st A1 c= A2 & B1 c= B2 holds
ex F being Function of (thin_cylinders A1,B1),(thin_cylinders A2,B2) st
for x being set st x in thin_cylinders A1,B1 holds
ex Bo being Subset of B1 ex yo1 being Function of Bo,A1 ex yo2 being Function of Bo,A2 st
( Bo is finite & yo1 = yo2 & x = cylinder0 A1,B1,Bo,yo1 & F . x = cylinder0 A2,B2,Bo,yo2 )

let B1, B2 be set ; :: thesis: ( A1 c= A2 & B1 c= B2 implies ex F being Function of (thin_cylinders A1,B1),(thin_cylinders A2,B2) st
for x being set st x in thin_cylinders A1,B1 holds
ex Bo being Subset of B1 ex yo1 being Function of Bo,A1 ex yo2 being Function of Bo,A2 st
( Bo is finite & yo1 = yo2 & x = cylinder0 A1,B1,Bo,yo1 & F . x = cylinder0 A2,B2,Bo,yo2 ) )

assume AS: ( A1 c= A2 & B1 c= B2 ) ; :: thesis: ex F being Function of (thin_cylinders A1,B1),(thin_cylinders A2,B2) st
for x being set st x in thin_cylinders A1,B1 holds
ex Bo being Subset of B1 ex yo1 being Function of Bo,A1 ex yo2 being Function of Bo,A2 st
( Bo is finite & yo1 = yo2 & x = cylinder0 A1,B1,Bo,yo1 & F . x = cylinder0 A2,B2,Bo,yo2 )

defpred S1[ set , set ] means ex Bo being Subset of B1 ex yo1 being Function of Bo,A1 ex yo2 being Function of Bo,A2 st
( Bo is finite & yo1 = yo2 & $1 = cylinder0 A1,B1,Bo,yo1 & $2 = cylinder0 A2,B2,Bo,yo2 );
P1: now
let x be set ; :: thesis: ( x in thin_cylinders A1,B1 implies ex D2 being set st
( D2 in thin_cylinders A2,B2 & S1[x,D2] ) )

assume x in thin_cylinders A1,B1 ; :: thesis: ex D2 being set st
( D2 in thin_cylinders A2,B2 & S1[x,D2] )

then ex D being Subset of (Funcs B1,A1) st
( x = D & D is thin_cylinder of A1,B1 ) ;
then reconsider D1 = x as thin_cylinder of A1,B1 ;
consider Bo being Subset of B1, yo1 being Function of Bo,A1 such that
P2: ( Bo is finite & D1 = cylinder0 A1,B1,Bo,yo1 ) by Def21;
D13: Bo c= B2 by AS, XBOOLE_1:1;
reconsider yo2 = yo1 as Function of Bo,A2 by AS, FUNCT_2:9;
set D2 = cylinder0 A2,B2,Bo,yo2;
XXX: cylinder0 A2,B2,Bo,yo2 is thin_cylinder of A2,B2 by P2, D13, Def21;
reconsider D2 = cylinder0 A2,B2,Bo,yo2 as set ;
take D2 = D2; :: thesis: ( D2 in thin_cylinders A2,B2 & S1[x,D2] )
thus ( D2 in thin_cylinders A2,B2 & S1[x,D2] ) by P2, XXX; :: thesis: verum
end;
consider F being Function of (thin_cylinders A1,B1),(thin_cylinders A2,B2) such that
P2: for x being set st x in thin_cylinders A1,B1 holds
S1[x,F . x] from FUNCT_2:sch 1(P1);
take F ; :: thesis: for x being set st x in thin_cylinders A1,B1 holds
ex Bo being Subset of B1 ex yo1 being Function of Bo,A1 ex yo2 being Function of Bo,A2 st
( Bo is finite & yo1 = yo2 & x = cylinder0 A1,B1,Bo,yo1 & F . x = cylinder0 A2,B2,Bo,yo2 )

thus for x being set st x in thin_cylinders A1,B1 holds
ex Bo being Subset of B1 ex yo1 being Function of Bo,A1 ex yo2 being Function of Bo,A2 st
( Bo is finite & yo1 = yo2 & x = cylinder0 A1,B1,Bo,yo1 & F . x = cylinder0 A2,B2,Bo,yo2 ) by P2; :: thesis: verum