@article{BS-On-The-Complexity-Of-Counting-Components-Of-Algebraic-Varieties, Title = {On the Complexity of Counting Components of Algebraic Varieties}, Author = {Peter Bürgisser and Peter Scheiblechner}, Pages = {1114-1136}, Year = {2009}, Journal = {Journal of Symbolic Computation}, Volume = {44}, Number = {9}, Abstract = {We give a uniform method for the two problems #CC_C and #IC_C of counting the connected and irreducible components of complex algebraic varieties, respectively. Our algorithms are purely algebraic, i.e., they use only the field structure of C. They work in parallel polynomial time, i.e., they can be implemented by algebraic circuits of polynomial depth. The design of our algorithms relies on the concept of algebraic differential forms. A further important building block is an algorithm of Szanto computing a variant of characteristic sets. Furthermore, we use these methods to obtain a parallel polynomial time algorithm for computing the Hilbert polynomial of a projective variety which is arithmetically Cohen-Macaulay.}, Url = {http://www3.math.tu-berlin.de/algebra/work/count-comp.pdf}, Url2 = {http://www.sciencedirect.com/science/article/pii/S0747717109000133} }