My fault. Loops (in the sense of self-intersections) are not a problem. Drop rule B(2)! What I had in mind was roundabouts. They are not loops. Thy are special cases of the rule B(3)
On 3 May 2018 at 19:10, marc marc <[email protected]> wrote: > "impossible" only due to missing tools to be able to do the job > and the time it take do it "by hand" > try to order this one http://www.openstreetmap.org/relation/1744381 > I spent a little time sorting these members, but it's a waste, > it's deteriorating faster than it's getting better. > > Le 03. 05. 18 à 18:49, Colin Smale a écrit : > > Why does a loop make it impossible to sort the ways? It implies that a > > section of the route is present twice in the relation, but there is > > surely no distinction between the first traversal of a way and the > > second traversal? > > > > > > On 2018-05-03 18:42, Volker Schmidt wrote: > > > >> I will try to explain this in a more systematic way: > >> > >> Routes belong to either of two categories: > >> (A) Those whose members can be sorted into a single ordered sequence > >> (B) Those that cannot be sorted into a single ordered sequence of > members > >> Sorting makes only sense for category (A) > >> Routes of type (B) can be subdivided into routes of type (A), each of > >> which can be sorted, but the overall route can not be sorted. > >> > >> Routes are of type (A) if > >> (1) the path from begin to end is identical to the reverse path with > >> all members traversed in the reverse order and in the opposite direction > >> or > >> (2) all members have the role forward > >> or > >> (3) all members have the role backward > >> > >> Any route > >> (1) that has more than two ends > >> or > >> (2) that contains any loop (except the case that the entire route is a > >> single loop) > >> or > >> (3) that contains any element with role forword or role backward > >> (except the cases of all-forward or all-backward) > >> or > >> (4) that contains node or area elements > >> is of type B > >> > >> I am not sure if I have taken care of all cases - please complete as > >> necessary > >> > >> > >> > >> _______________________________________________ > >> Tagging mailing list > >> [email protected] <mailto:[email protected]> > >> https://lists.openstreetmap.org/listinfo/tagging > > > > > > _______________________________________________ > > Tagging mailing list > > [email protected] > > https://lists.openstreetmap.org/listinfo/tagging > > > > _______________________________________________ > Tagging mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/tagging >
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