  Generalized Schmidt decomposition of pure three-qubit states has four
positive and one complex coefficients. In contrast to the bipartite case, they
are not arbitrary and the largest Schmidt coefficient restricts severely other
coefficients. We derive a nonstrict inequality between three-qubit Schmidt
coefficients, where the largest coefficient defines the least upper bound for
the three nondiagonal coefficients or, equivalently, the three nondiagonal
coefficients together define the greatest lower bound for the largest
coefficient. In addition, we show the existence of another inequality which
should establish an upper bound for the remaining Schmidt coefficient.
