On tangent cones at infinity of algebraic varieties

Abstract

In this paper, we establish the following version at infinity of Whitney's theorem [6, 7]: Geometric and algebraic tangent cones at infinity of complex algebraic varieties coincide. The proof of this fact is based on a geometric characterization of geometric tangent cones at infinity and using the global Łojasiewicz inequality with explicit exponents for complex algebraic varieties. We also show that tangent cones at infinity of complex algebraic varieties can be computed using Gröbner bases.

9 pages, Section 3 re-written, one reference added, acknowledgment updated with thanks to Prof. Gert-Martin Greuel