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From: Jeremy Siek (jsiek_at_[hidden])
Date: 2003-10-30 20:32:27

Hi Vladimir,

On Wednesday, October 29, 2003, at 08:31 PM, Vladimir Prus wrote:
> That's good. However, I think that the test can be simplified.
> Consider the
> following (pseudo)code.
> for i in vertices(g)
> for j in vertices(g)
> bool tc_has_edge;
> tie(..., tc_has_edge) = edge(i, j, tc);
> bool should_have_edge = is_reachable(i, j, g)
> if (tc_has_edge != should_have_edge)
> return false;
> I believe it's equivivalent to the current test.

Yes, that is nicer.

> Also, there's still a problem with is_reachable(i, i), which always
> returns
> true -- I'm not sure how real it is, yet.

Ok, I think I can solve that...

> Also if I remove
> if (components[component_number[*i]].size() == 1)
> check from my new code, the test still passes. Revision 1.2 did not
> pass.
> The reason is that the new code only cares if there's edge in
> transitive
> closure, but allows 2 parallel edges -- that's precisely what the "if"
> statement tries to avoid. How can we test for this problem?

I just checked in a new version of the test that tries to solve this.

> Great! The only nit is that the code now have tabs. I've removed them
> in *.w
> source, maybe I'll commit the change and you'll regenerate hpp?



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