We show that the Schwarz alternating procedure offers a good algorithm
for the numerical solution of singular perturbation problems, provide
d the domain decomposition is properly designed to resolve the boundar
y and transition layers. We give sharp estimates for the optimal posit
ion of the domain boundaries and study the convergence rates of the al
gorithm for various linear second-order singular perturbation problems
. We report on implementation results for a turning-point problem and
a combustion problem.