1. Movement is often conditional on environmental parameters and behavioural phenotype. A reasonable assumption is that individuals behave as random walkers, when environment and behaviour are fixed.

Vol. 18, Analytic and Geometric Stochastics: Papers in Honour of G. E. H. Reuter (Dec., 1986), pp. 73-85 (13 pages) A construction due to Asmussen and Jacobsen is generalised so as to produce ...