%P R2029-R2032 %T Optimal path and directed percolation %V 53 %I American Physical Society %X An efficient transfer matrix technique is introduced to study directed optimal paths in two and three dimensions. The roughness exponent ? is 0.6325?0.0007 for the two-dimensional case and ?=0.555?0.008 for the three-dimensional one, in agreement with the recent conjecture ?=??/??, where ?? and ?? are the correlation length exponents of directed percolation. Exactly solvable examples are also analyzed. %D 1996 %L eprints1183 %K PACS: 05.40.+j, 02.50.-r %A Paolo Rios %A Guido Caldarelli %A Amos Maritan %A Flavio Seno %R 10.1103/PhysRevE.53.R2029 %N 3 %J Physical Review E