consider l, r, i being BinOp of {{}}, d being Relation of ({{}} *),{{}};
take typestr(# {{}},l,r,i,d #) ; :: thesis: ( not typestr(# {{}},l,r,i,d #) is empty & typestr(# {{}},l,r,i,d #) is strict )
thus not the carrier of typestr(# {{}},l,r,i,d #) is empty ; :: according to STRUCT_0:def 1 :: thesis: typestr(# {{}},l,r,i,d #) is strict
thus typestr(# {{}},l,r,i,d #) is strict ; :: thesis: verum