On non-strictly hyperbolic systems and models of natural sciences reducible to them

We show that many important natural science models in their mathematical formulation can be reduced to non-strictly hyperbolic systems of the same kind. This allows the same methods to be applied to them so that some essential results concerning a particular model can be obtained as corollaries of general theorems. However, in each case, the models have their own characteristics. The article contains an overview of both potentially applicable methods, as well as known results obtained for a particular model. In addition, we introduce new models and obtain results for them.