let F be non empty finite set ; :: thesis: for A being non-empty FinSequence of bool F
for i, j being Element of NAT
for B being Singlification of A,i
for C being Singlification of B,j st i in dom A & j in dom A & C . i <> {} & B . j <> {} holds
( C is Singlification of A,j & C is Singlification of A,i )

let A be non-empty FinSequence of bool F; :: thesis: for i, j being Element of NAT
for B being Singlification of A,i
for C being Singlification of B,j st i in dom A & j in dom A & C . i <> {} & B . j <> {} holds
( C is Singlification of A,j & C is Singlification of A,i )

let i, j be Element of NAT ; :: thesis: for B being Singlification of A,i
for C being Singlification of B,j st i in dom A & j in dom A & C . i <> {} & B . j <> {} holds
( C is Singlification of A,j & C is Singlification of A,i )

let B be Singlification of A,i; :: thesis: for C being Singlification of B,j st i in dom A & j in dom A & C . i <> {} & B . j <> {} holds
( C is Singlification of A,j & C is Singlification of A,i )

let C be Singlification of B,j; :: thesis: ( i in dom A & j in dom A & C . i <> {} & B . j <> {} implies ( C is Singlification of A,j & C is Singlification of A,i ) )
assume that
A1: i in dom A and
A2: j in dom A and
A3: C . i <> {} and
A4: B . j <> {} ; :: thesis: ( C is Singlification of A,j & C is Singlification of A,i )
A5: dom B = dom A by Def6;
then A6: C . i c= B . i by A1, Def6;
A7: A . i <> {} by A1, Th2;
then card (B . i) = 1 by A1, Def7;
then A8: card (C . i) = 1 by A3, A6, NAT_1:25, NAT_1:43;
A9: A . j <> {} by A2, Th2;
A10: C is Reduction of A by Th22;
card (C . j) = 1 by A2, A4, A5, Def7;
hence ( C is Singlification of A,j & C is Singlification of A,i ) by A1, A2, A7, A9, A10, A8, Def7; :: thesis: verum