Abstract. We use very efficient algorithms to calculate low-density series for bond and site percolation on the directed triangular, honeycomb, kagomé and (4.8²) lattices. Analysis of the series yields accurate estimates of the critical point p_c and various critical exponents. The exponent estimates differ only in the 5th digit, thus providing strong numerical evidence for the expected universality of the critical exponents for directed percolation problems. In addition we also study the non-physical singularities of the series.

PACS numbers: 05.50.+q, 05.70.Jk, 05.70.Ln, 05.10.−a

Print publication: Issue 27 (9 July 2004)
Received 15 April 2004
Published 22 June 2004