Based on singular perturbation analysis of nonlinear PDEs, we can get
an approximate solution of the equation, constructed from a solution o
f the reduced equation associated with the given nonlinear PDE, and co
rrection terms corresponding to boundary layers and interior layers. B
y applying the above methods a set of rules to determine a stable part
ition of a domain can be built. Based on the set of rules the search f
or all possible stable partitions is implemented by a production syste
m which travels a graph of a given domain. In this paper only elliptic
equations are discussed.