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Tarjan reporting false loops - fix 2080845#212

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mtygesen wants to merge 11 commits into
TAPAAL:mainfrom
mtygesen:tarjan-false-loop-2080845
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Tarjan reporting false loops - fix 2080845#212
mtygesen wants to merge 11 commits into
TAPAAL:mainfrom
mtygesen:tarjan-false-loop-2080845

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@mtygesen

@mtygesen mtygesen commented Oct 8, 2025

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@srba srba self-requested a review October 8, 2025 19:30

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The fix is wrong, if you open the net from this bug report

https://bugs.launchpad.net/tapaal/+bug/2127171

and ask the LTL query

E (G ((F TAPN1.P6 = 1) and (F TAPN1.P5 = 1)))

using Tarjen, it gives a finite trace which is wrong - compare with the trace returned without Tarjan that is correct.

@srba srba self-requested a review October 9, 2025 20:57

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The attached query on the model returns a trace that is not executable in the net.

test1.tapn.zip

@srba srba self-requested a review October 16, 2025 12:59

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Fixes all the issues but there is a new bug introduce - see the attached net and run the second query - this gives a trace that is not executable. This works correctly in the current main, so it was introduced in this PR.
test2.tapn.zip

@srba srba self-requested a review October 22, 2025 15:16

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The trace changes in the PR also cause wrong verifications answers for LTL with Tarjan, see this bug report
https://bugs.launchpad.net/tapaal/+bug/2131082

@srba srba self-requested a review November 13, 2025 08:50
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2 participants