23-12-2025, 11:08 AM
Am I right in understanding that these PCA plots are computed just on character pair frequencies? And that these plots are being used to judge how A-like or B-like certain pages are? It seems to me that this might lead to wrong conclusions.
For example look at the following PCA plot, from quires 8, 13, 20.
It shows You are not allowed to view links. Register or Login to view. and You are not allowed to view links. Register or Login to view. in the middle of the quire 20 domain of points. You might conclude that these two pages are representative of quire 20. Yet a different PCA plot shows these two pages outside of the quire 20 domain. Also You are not allowed to view links. Register or Login to view. and You are not allowed to view links. Register or Login to view. which were previously distant from quire 20 and are now much closer.
The difference in the plots is that the second was computed using additional measures: frequencies of whole words, prefixes, suffices, character end pairs ( first character of word + last character ), bridge pairs ( last character of word + first character of following word ), gallows frequencies, frequency of words containing r, d .
Surely you need to include some such additional measures alongside character pairs when deciding if groups of pages are related.
For example look at the following PCA plot, from quires 8, 13, 20.
It shows You are not allowed to view links. Register or Login to view. and You are not allowed to view links. Register or Login to view. in the middle of the quire 20 domain of points. You might conclude that these two pages are representative of quire 20. Yet a different PCA plot shows these two pages outside of the quire 20 domain. Also You are not allowed to view links. Register or Login to view. and You are not allowed to view links. Register or Login to view. which were previously distant from quire 20 and are now much closer.
The difference in the plots is that the second was computed using additional measures: frequencies of whole words, prefixes, suffices, character end pairs ( first character of word + last character ), bridge pairs ( last character of word + first character of following word ), gallows frequencies, frequency of words containing r, d .
Surely you need to include some such additional measures alongside character pairs when deciding if groups of pages are related.