The Naibbe cipher

[pfeaster]

Can this approach explain line-as-a-functional-unit properties, such as the tendency of certain characters and combinations to appear near/at the beginning or end of lines?

Not as it stands, but maybe a variant on it could.  The playing-card mechanism is designed to impose a frequency ratio among choices from the different tables, and it's good at accomplishing that -- but, applied strictly as described, it would also create flat ciphertexts with none of the regional variation we know and love from our holidays on Tavie's island.

There could be arbitrary rules such as (1) when encoding the first line of a paragraph, draw from this table; (2) when encoding the first vord of a line, draw from that table; (3) when encoding the last vord of a line, draw from that other table.  But that doesn't strike me as a very satisfying solution, since it doesn't offer any real explanation for such a practice.

Michael hinted that an explanation for repeated vords (or strings of similar vords) could be that the same table was used repeatedly.  And I suppose the same table would occasionally have been used several times in a row through sheer chance in a manuscript of this length.  But often enough to produce the patterns of repetition we see, without some further contributing factor?  I'm not sure.

An alternative mechanism consistent with Michael's approach (I think) would be for tables to be chosen dynamically based on the previous output of the ciphering mechanism.  As long as such a mechanism produced the same ratios as the playing cards, it could preserve the statistical advantages of the Naibbe system while simultaneously opening up an entry point for higher-level patterning to emerge.  If the previous vord contains x, switch to the next table when encoding the next vord -- that sort of thing.  Or it could even be based on choosing the table(s) used to encode a nearby vord -- a meaning-bearing variant on Timm-Schinner self-citation?

Another possibility would be for the switch of tables itself to convey information.

When it comes to LAAFU properties, something similar could be in play.  The choice of table for the start of a line could be constrained by different factors than subsequent choices.  Certain choices could naturally become more or less probable as a line progresses (say, the cumulative effect of a repeated 45% or 55% chance).  And the last choice might likewise have special constraints.  This could be worth playing around with.

I'm not sure it's essential for the plaintext units in a system like the one Michael describes to be unigrams and bigrams, specifically -- it seems to me that they could be any values, so long as they occur primarily in units encoded by one ciphertext vord or by two ciphertext affixes.  With that in mind, there might be relevant sequences that are more or less likely to occur at the beginning or end of a line, such that LAAFU effects would be artifacts of line chunking.  I've speculated about this myself in terms of syllabic encoding (for example, NTI might be common mid-line but not line-start); but it might also be applicable to some variant of Naibbe.  That could be interesting to model.

I thought the ground rules Michael laid out at the start of his presentation were excellent, and I'd recommend keeping them in force when exploring solutions to line and paragraph patterning.  Ideally, enciphered lines should show LAAFU effects with no special effort on the encipherer's part to impose them and no special plaintext characteristics behind them.