[Article] Voynich Manuscript: Numeric Enigma?

[MarcoP]

Thank you for pointing out this paper, lurker!

At the end of page 1, they misquote Rene saying that

thanks to the carbon-dating method, an approximate date of its creation has been established: 1405—1435 (Zandbergen 2016).

Of course, the correct date range is 1404-1438.

I am delighted to see [Trinity] MS O.2.48 mentioned as a relevant parallel for the Voynich herbal (Figure 1). Here the authors fail to mention both the Trinity College and Rene Zandbergen, who pointed out the Trinity herbal on this forum.

Page 3:

Before we step into the analysis, first we formalize preprocessing of the Takeshi Takahashi’s transliteration (Takahashi 1999) of the Voynich Manuscript, which we used for the analysis and which we found to be the most thorough

I would like to know why they think that Takahashi's transliteration is better than Zanbergen and Landini's. ZL adds the text on the Rosettes diagram and the difference between certain and uncertain spaces.

I am very perplexed about the cipher system they propose:

• some of the characters are seen as abbreviations (they call them "ligatures") and stand for multiple characters
  
• once the "ligatures" have been expanded, sequences of three cipher characters (which they reduce to 10 and interpret as "digits") should be interpreted as single plain-text characters (basically a verbose cipher)
  
• each plain-text character can be represented by several (e.g. 27) "digit" sequences
  
• spaces are not significant
  

The system is "based on a slightly modified Trithemius steganographic and numeric code" (created more than half a century later than the VMS).

This complex cipher results in a huge number of possible ways to encode a single word:

the word “hello” could be rewritten into 27×27×27×27×27=27^5=14,348,907 variants

One would expect that this results in Type/Token Ratio TTR=1, i.e. a text that is only made of hapax legomena. So why does Voynichese words behave similarly to actual words, with more or less "normal" TTR, word entropy, Zipfian distribution?

Answer:

...the digit substitutes are picked arbitrarily by coders’ will. This may explain the observed autocorrelations of all the symbols and repeated words. First, the autocorrelations might be a consequence of a habit of picking specific substitutes for single digits or for larger blocks – like letters or words: picking the substitutes randomly each time is mentally exhausting, building a habit accelerates the coding work. Once such habit is established, it boosts the frequency of the substitute symbols locally. Such habits may also naturally fade off as the coder notices the repetition and builds up new habits. Such habits may also explain the proposed languages A and B, as the two main coders could encode the text by their own habits before the text was rewritten by individual scribers (Currier 1976).

It seems contradictory to speculate that the arbitrary choices of the scribes were systematic. If all observable patterns (low character entropy, repeated words, Currier languages...) are explained away as arbitrary preferences, what is the point of looking for patterns as evidence of specific encoding methods as the paper does? The idea that encoders tended to have systematic preferences is also historically inaccurate. Homophones in diplomatic ciphers were picked arbitrarily, but this was done in such a way that cipher characters tend to appear with more or less even frequencies: that is why homophones were introduced in the first place.

Finally, we already discussed that a verbose cipher in which spaces are not significant would be extremely hard to solve. The authors add that the method they propose could also be made largely unreadable by small encoding (or decoding) errors made in the process:

Another interesting property of this code is its fragility: misreading just one symbol shifts the whole code, making the result of the text unreadable (until hitting new line, paragraph, or any resetting sequence – which may be related to Currier’s statement that a voynichese line might be a functional entity (1976: 23) – or until making another mistake repairing the reading frame). In combination with the probable fact that we do not read the Voynich symbols right, we may easily fail to read the code even when knowing it is present.