[Retros] What does C+ mean?

Thomas Maeder maeder at glue.ch
Wed Nov 16 04:04:49 EST 2005

Renny Bosch wrote:

> Could someone please explain what the designation "C+" means? I suspect it

> has something to do with uniqueness or minimum length but am not sure. If

> it is explained in the Retro Corner Glossary please tell me under what

> heading.

The supposed meaning is "Correctness verified by a computer program."

But it's a good idea to always take this "information" with a grain of salt.
From my (Spokesman of the Sub-Committee for Computer Matters) oral report to
the PCCC this year:

The sub-committee [...] reminds problemists not to read too much into the "C+"
tag written next to a problem; in the worst case, this tag only means that
somebody tried to use a computer to obtain some information about the
correctness of the problem.


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