set D = the non empty set ;
set f = the Relation of the non empty set ;
take RelStr(# the non empty set , the Relation of the non empty set #) ; :: thesis: ( not RelStr(# the non empty set , the Relation of the non empty set #) is empty & RelStr(# the non empty set , the Relation of the non empty set #) is strict )
thus not the carrier of RelStr(# the non empty set , the Relation of the non empty set #) is empty ; :: according to STRUCT_0:def 1 :: thesis: RelStr(# the non empty set , the Relation of the non empty set #) is strict
thus RelStr(# the non empty set , the Relation of the non empty set #) is strict ; :: thesis: verum