5

 Two polynomials m(s) and n(s) are coprime if the only common factors are
constants.
 Two transfer functions m(s) and n(s) in RH_{¥} are
coprime if the only common factors are stable and invertible transfer
functions (units): I.e. h,
mh^{1}, nh^{1} Î RH_{¥} _ h^{1} Î RH_{¥}

Equivalent, there exists x,y Î RH_{¥}_{ } such that
 xm+yn=1.
 Matrices M and N in RH_{¥} are right coprime if there exist matrices X_{r}
and Y_{r} in RH_{¥} such that
 Matrices and in RH_{¥} are left coprime if there exist matrices X_{l}
and Y_{l} in RH_{¥} such that
