[isabelle-dev] Towards the next release --- and release naming scheme

[Makarius]

We are slowly moving towards the next Isabelle release, a second one this
year: this special situation happens every few years, because the distance
between releases is constant at 8-10 months. (I always try to shorten the
interval a bit, but rarely manage.)

The overall plan is like this:

  * Sun 03-Oct-2021: rough RC0 as "preview"

  * 01-Nov-2021: official RC1

  * total of 4-6 RCs for consolidation

  * final immutable release before 15-Dec-2021


The remaining question right now is if we want to venture at a change of the
release naming scheme. According to the existing scheme, it would be
"Isabelle2021-1 (December 2021)". Afterwards there would be "Isabelle2022
(October 2022)".

Some decades ago, Larry treated the year like a major version number, with
occasional bumps added via -1, -2, -3. E.g. see the long and successful series
of Isabelle94-n, even with a few releases lost in time and space:
https://isabelle.in.tum.de/download_past.html

After 2011, this scheme no longer made any sense: So many great things were
already present in the Isabelle corpus, that made it hard to justify a major
release number increase again. So instead of being stuck with 2011
indefinitely (which was after addition of PIDE), and merely have variations
2011-1, 2011-2, 2011-3, 2011-4, ..., we followed a modified scheme where the
year is always that of the calender and tags -1, -2 distinguish multiple
releases per year.

[3 releases actually did happen in 2013, because Isabelle2013-1 (November
2013) had serious problems in PIDE that had to be addressed in Isabelle2013-2
(December 2013). Like in the Roman Empire or the Habsburg Empire, a "3 Emporer
year" is actually something very bad, and to be avoided at all cost.]


In summary we could venture at a slight reform as follows:

  * Releases are always named after the calender year + month of final
appearance, lets say "Isabelle2021-Dec" for the coming release: Following the
naming scheme for months "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
"Aug", "Sep", "Oct", "Nov", "Dec" that is used in other places of Isabelle
already. An alternative is to spell out the month, e.g. Isabelle2021-December.

  * This year + month scheme would continue uniformly in the future,
independently of the number of releases per year. So after "Isabelle2021-Dec"
would come something like "Isabelle2022-Oct".

  * The explanatory add-on like "(December 2021)" disappears, being now
redundant. IIRC correctly, I had proposed this to Larry on the occasion of
"Isabelle94-7 (November 1996)" to make it look a bit less confusing to our
growing user community.


How is the feeling for this idea after so much text, which only scratches many
delicate points of our long history?

What name should it be?

   Isabelle2021-1 (December 2021)
   Isabelle2021-Dec
   Isabelle2021-December


	Makarius