The evolution of P/F vs T/K raises important questions

[Jorge_Stolfi]

I agree with you that p/f are not the same as ke/te. Some time ago I tested this hypothesis by measuring the (root-mean-square, Euclidean) distances of the distributions of the preceding and of the following character for the glyphs 'p', 'f', 'ke' and 'te' and they turned out to be quite dissimilar. 'ke' and 'te' were instead most similar to... themselves. The post is You are not allowed to view links. Register or Login to view.

I explored a little more the behaviour of 'k' and 't' ('p' and 'f' are rare glyphs and I'm not sure if statistics on those would be reliable), which are quite similar (by the above metric) among them: it turned out 'ok' and 'ot' are even more close than 'k', 't' alone, and removing 'ok'/'ot' removes also most of the similarity between 'k' and 't'.

I did not follow all the discussion on the "puffs" that went on for the last 20 years.  But the conclusion I recall from my own statistics was

• in their prev-char distributions, p/f resemble both k/t and ke/te;
  
• in their next-char distributions, on the other hand, they resemble ke/te much more than k/t
  

One thing that people should keep in mind when researching this question is that the use of p/f is probably not algorithmic and not invertible.  They are obviously fancy versions of some glyphs or digraphs, that are used on the head line of a parag to flag it as a head line, and occasionally on other lines too.  They generally occur inside words at positions where we expect k/t to occur; but also too often as the first glyph of a parag.  So they may have been used as replacements of other glyphs too (like d).  The decision to replace each glyph or digraph by p/f in head lines probably was made by the Scribe and/or the Author at random, with unequal probabilities for different glyphs; which would explain the puzzling statistics.

Also, last year I got the idea that maybe p/f with a straight arm are fancy version of k/t, whereas p/f with a hooked arm are fancy versions of ke/te.  That could explain why the nature of p/f remained baffling.  Imagine the zoologists' confusion about the diet and habits of geese if they dismissed as irrelevant individual variations the visual differences between geese and seagulls.

So I spent several days revising the p/f in the interlinear file and changing them to w/z if they had a hooked arm. But I never finished that project, because I could not avoid noticing that the degree of "hooking" was a continuous variable rather than a binary trait.  It did seem like it was just a meaningless calligraphic flourish, as every transcriber (me included) had previously assumed.  

But maybe I should go back and actually compute the statistics for the pages I managed to revise.  For one thing, it is quite possible that the apparent continuity of "hooking" was another consequence of the fading ink and subsequent global restoration...

All the best, --stolfi