We consider the eigenvalues of the three-dimensional Weyl operator defined in
terms of the (Euclidean) Ashtekar variables, and we study their dependence on
the gravitational field. We notice that these eigenvalues can be used as
gravitational variables, and derive explicit formulas for their Poisson
brackets and their time evolution.Comment: 15 pages, LaTex style, preprint UPRF-94-39