In many complex systems one can distinguish fast and slow processes with radically di?erent velocities. In mathematical models based on di?er- tialequations, suchtwo-scalesystemscanbedescribedbyintroducingexpl- itly a small parameter?on the left-hand side ofstate equationsfor the fast variables, and these equationsare referredto assingularly perturbed. Surpr- ingly, this kind of equation attracted attention relatively recently (the idea of distinguishing fast and slow movements is, apparently, much older). Robert O Malley, in comments to his book, attributes the originof the whole...

In many complex systems one can distinguish fast and slow processes with radically di?erent velocities. In mathematical models based on di?er- tialequations, suchtwo-scalesystemscanbedescribedbyintroducingexpl- itly a small parameter?on the left-hand side ofstate equationsfor the fast variables, and these equationsare referredto assingularly perturbed. Surpr- ingly, this kind of equation attracted attention relatively recently (the idea of distinguishing fast and slow movements is, apparently, much older). Robert O Malley, in comments to his book, attributes the originof the whole...