We study the ergodic theory of a multitype contact process with equal death
rates and unequal birth rates on the d-dimensional integer lattice and
regular trees. We prove that for birth rates in a certain interval there is
coexistence on the tree, which by a result of Neuhauser is not possible on the
lattice. We also prove a complete convergence result when the larger birth rate
falls outside of this interval.Comment: Published in at http://dx.doi.org/10.1214/08-AOP422 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
