MichelleL11, the fragment cited by you describes the situation when two cleartext letters are merged into the same ciphertext letter. So it's not applicable to geoffreycaveney's post about merging EVA-or or EVA-ol, but rather to his earlier post about merging p and b, t and d,... into the same ciphertext letters (in our case into Voynich letters).
This merging will decrease the entropy (which is logical, since number of symbols decreases).
However the difference (h1-h2) behaves differently. If probabilities of p and b are the same independently of the previous letter ("independent of context") then the impact of merging them is the same both for h1 and h2, so (h1-h2) will not change. The world is not ideal, but these are merging/splitting operation properties by default.
As for merging Voynich letters I think it's just trial and error method. One merging pair can produce somewhat predictable result, but the combination of merges is highly volatile. Not speaking about the logic: why qok and qot are being merged, but qop and qof are not?
This merging will decrease the entropy (which is logical, since number of symbols decreases).
However the difference (h1-h2) behaves differently. If probabilities of p and b are the same independently of the previous letter ("independent of context") then the impact of merging them is the same both for h1 and h2, so (h1-h2) will not change. The world is not ideal, but these are merging/splitting operation properties by default.
As for merging Voynich letters I think it's just trial and error method. One merging pair can produce somewhat predictable result, but the combination of merges is highly volatile. Not speaking about the logic: why qok and qot are being merged, but qop and qof are not?
![[+]](https://www.voynich.ninja/images/collapse_collapsed.png)