Vyacheslav S. KALNITSKY
Chair of Higher Geometry,
Department of Mathematics and Mechanics,
Saint-Petersburg State University,
28 Universitetsky Av.,
198504 Saint-Petersburg, RUSSIA
E-mail: skalnitsky@hotmail.com

Spray algebra

The infinite dimensional tensor algebra of polylinear symmetries of spray of affine connection is described. Components of this graded algebra correspond different geometrical aspects of symmetry. We are studying the structure of the algebra, describing "standard" solutions of natural differential operators appeared and  introduce the notion of "Bochner type" obstacles for symmetry.