The Naibbe cipher

[magnesium]

I should also note: If memory serves, most labels are uncommon word types. Within the Naibbe cipher, the overwhelming majority of the word types outside the 100 most common word types represent plaintext bigrams, with an average verbosity of ~2.5 glyphs/letter (though with some being much more verbose), consistent with the upper bound of your suggested verbosity range. The ultimate reason why the cipher encrypts unigrams as entire words is because if this is in place, it becomes much easier to achieve Voynich B's anomalously flat frequency-rank distribution of word types (see Bowern and Lindemann (2021)).

I don't know whether it's been done, but if it hasn't, it would be interesting to study the word-level statistics of the labels specifically and see how much they differ from the rest of the VMS. Any which way, the labels pose challenges for the ciphertext hypothesis: Assuming for the moment that the token and type length distributions of labels are consistent with the rest of the manuscript, well more than half of labels would have to be <5 letters long given your suggested verbosity ranges, which in many cases would still imply a weirdly short label.

Yes, this is true. But I said "verbosity not exceeding", so I'm not suggesting a range, more like a fuzzy upper bound. I agree that to have comfortable lengths of the labels there should be a closer to 1:1 correspondence. There is of course a chance that labels are only indices (fig. A, fig. B), referenced in the texts, in which case they can be as short as needed.

I agree that through the lens of the Naibbe cipher, the labels in the VMS look weirdly short and uninformative (see Section 4.4 of the paper). One potential workaround is that at least some sets of labels are meant to be read as single interspersed messages. Consider, for example, the star chart on f68r2, whose 24 star labels can be theoretically read left-to-right as 8 rows of text...

There are cases where it's not obvious how to parse the labels sequentially, for example:

I freely admit that this is not a complete solution.

However, do you consider it's actually possible that some similar scheme was used for the Voynich Manuscript? If so, what would you call the strongest hints pointing in this direction?

I don't have a strong opinion on any particular labeling scheme, though I do like your suggestion of an indexing "Fig. A" approach. My observations on the labels stem from what I find needs to work globally to get Latin and Italian n-grams to very reliably take on word-level properties of the VMS. To achieve VMS-like character entropy and conditional character entropy very reliably, a cipher benefits from being verbose in the neighborhood of ~2.5 glyphs/letter. But the second you do that, the second it becomes easy to encrypt trigrams and longer n-grams as ciphertext tokens of length ≥8, and the VMS places tight constraints on how many unique Voynichese word types get that long. As a result, within this particular construction, the plaintext has to be mostly unigrams and bigrams—including the labels.

Zooming out, this is exactly the kind of discussion I was hoping the Naibbe cipher would create. I don't assert that the Naibbe cipher precisely reflects how the VMS was created, nor do I assert that Voynichese even contains meaning. But as a reference model for VMS text generation, the Naibbe cipher implies that individual labels don't contain much plaintext at all. Given that, are there viable abbreviation schemes or alternate ways of interpreting the labels? If not, then maybe that's a point in favor of the VMS being gibberish.