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