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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Standard Set types don't support a feature
Date: Sun, 29 Oct 2017 18:10:01 +0100
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Date: 2017-10-29T18:10:01+01:00
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On 2017-10-29 17:15, Victor Porton wrote:
> I want to represent a directed graph as a set of pairs (a,b) where a and b
> are vertices.

Any directed graph is a set of pairs.

> To efficiently find a transitive closure, I want to search for the first
> element (a,x) of the graph with a given starting vertex a.
> 
> It seems that standard containers do not support it (except of silly broken
> use of keys).

Graph is not a container, not in the sense an array or matrix is.

> What would you suggest? Maybe should I use Bochs?

Simple components have an implementation of directed graphs:

    http://www.dmitry-kazakov.de/ada/components.htm#directed_graphs

[ Transitive closure requires no evaluation, a node = graph rooted in 
this node ]

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de