[Bug 286740] ports-mgmt/pkg: 2.1.2 Cannot solve problem using SAT solver, trying another plan

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=286740

--- Comment #7 from Mark Millard <marklmi26-fbsd@yahoo.com> ---
(In reply to p5B2EA84B3 from comment #6)

Also having a prefix indicating the
informational status that bapt has noted
here could work, say something like:

Informational note:
Could not solve the dependency constraints via
the minisat "SAT solver", so trying a different
way of handling the dependency related ordering.


It may well be that minisat is non-determistic
in some of its techniques for exploring the
solution space. (Also fits with dependency
constraints commonly having multiple distinct
solutions that are valid to find.) This can make
judging the consequences of interventions rather
difficult: randomness would also be involved.


Overall:

To my knowledge no one knows a way to avoid
the NP-complete nature of the problem from
sometimes having consequences one would
otherwise want to avoid, including some
uncertainty. Saying that there should be no
such problem does not provide any known
technique to provide what is requested
that does not get back into a NP-complete
issue as far as I can tell.

Thus, my emphasis on potential improvements
in the message, improvements that are tied
to the limited information available in
the software for the NP-compete problem.

It also may be that a man page needs to
present information and a reference to
such be in the messages produced at run
time. It is not a simple context.


Note:

If bapt reports differently for anything,
he has far more context than I do. Without
explicit evidence otherwise, believe bapt
generally, not me.

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