consider A being non empty set , a being BinOp of A, Z being Element of A, r being Function of [:A, the carrier of FS:],A;
take
RightModStr(# A,a,Z,r #)
; not RightModStr(# A,a,Z,r #) is empty
thus
not the carrier of RightModStr(# A,a,Z,r #) is empty
; STRUCT_0:def 1 verum