Abstract coarse structures were introduced by J.Ro. Subsequently, equivalent structures, called large scale structures were introduced by J.Dydak and C.Hoffland. This paper is devoted to a much simpler definition of majority of useful coarse structures. Namely, they are equivalence relations on the set of simple ends of sets equipped with a bounded structure. As an application we show that Gromov boundary of every hyperbolic space is an example of a Higson corona and each Freundenthal compactification is an example of a Higson compactification. 查看全文>>