Delta Cipher

[Fontanellean]

There are many different ways that could work, but it's a theory that to me seems attentive to many of the properties the text needs to have.

It's not nearly restrictive enough. You need more constraints than frequent self-similarity to explain Voynichese. Also ambiguous word breaks make ciphers relying on words unlikely. There is a workaround with a possible re-parsing of tokens ignoring spaces that would also explain the rigid word structure.

That particular example isn't restrictive enough, but I'm simply referring to the general family of delta ciphers. At least they predict a general trend toward word similarity and phrase similarity for someone lacking the aid of a computer. I just want to make sure anything I investigate is deep within a parameter space that hasn't been excluded.