On the classification of electromagnetic media

This paper reviews a topic of collaboration between the present author and professor F. Olyslager
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of the 1990's concerning the generalization of classes of electromagnetic media in which fields can be naturally decomposed in two noninteracting components. As a continuation to this research it is shown that the medium classes, originally defined in terms of three-dimensional Gibbsian dyadic algebra, can be introduced in a compact manner by applying four-dimensional multivector dyadic formalism. It is also shown that these classes are closed in the affine transformation.