A model was proposed for the interaction of dislocations in a honeycomb-like configuration. The formation of complex structures was predicted to occur when the 2 populations interacted. The system of conservation laws was found to degenerate into an elliptic system, and was therefore unstable in the region where such structures were expected to appear.

On the Modelling of Instabilities in Dislocation Interactions A.Carpio, S.J.Chapman: Philosophical Magazine B, 1998, 78[2], 155-7