We introduce a linear programming method to obtain bounds on the cardinality
of codes in Grassmannian spaces for the chordal distance. We obtain explicit
bounds, and an asymptotic bound that improves on the Hamming bound. Our
approach generalizes the approach originally developed by P. Delsarte and
Kabatianski-Levenshtein for compact two-point homogeneous spaces.Comment: 35 pages, 1 figur