let D be non empty set ; :: thesis: for d being Element of D holds <*d*> in 1 -tuples_on D
let d be Element of D; :: thesis: <*d*> in 1 -tuples_on D
<*d*> in { <*d1*> where d1 is Element of D : verum } ;
hence <*d*> in 1 -tuples_on D by Th94; :: thesis: verum