let D be non empty set ; :: thesis: for x1, x2, x3, x4, x5, x6, x7, x8 being Element of D holds <*x1,x2,x3,x4*> ^ <*x5,x6,x7,x8*> is Element of 8 -tuples_on D
let x1, x2, x3, x4, x5, x6, x7, x8 be Element of D; :: thesis: <*x1,x2,x3,x4*> ^ <*x5,x6,x7,x8*> is Element of 8 -tuples_on D
reconsider x1234 = <*x1,x2,x3,x4*> as Element of 4 -tuples_on D by LMGSEQ4;
reconsider x5678 = <*x5,x6,x7,x8*> as Element of 4 -tuples_on D by LMGSEQ4;
D c= D ;
hence <*x1,x2,x3,x4*> ^ <*x5,x6,x7,x8*> is Element of 8 -tuples_on D by FINSEQ_2:109; :: thesis: verum